Vehicle Details
Body Style
Truck
Engine
3.0L 6Cyl
Exterior Colour
Black
Interior Colour
Black
Transmission
Automatic
Drivetrain
4×4
Stock
18-260284
Fuel Type
Diesel
Trim Details
Crew Cab Short Box 4-Wheel Drive AT4
Description
2026 GMC Sierra AT4 Crew Cab Duramax Diesel – Onyx Black
Built for adventure but refined for everyday driving, the 2026 GMC Sierra AT4 Crew Cab blends off-road capability, premium technology, and legendary diesel performance. Finished in bold Onyx Black and riding on 20" machined aluminum wheels with Carbon Grey accents, this Sierra AT4 delivers the rugged styling and capability that define GMC’s premium off-road lineup.
With the powerful Duramax diesel engine and AT4-exclusive features, this truck is equally comfortable on the highway, job site, or exploring off the beaten path.
💪 Duramax 3.0L Turbo-Diesel Performance
At the heart of this Sierra AT4 is the efficient and powerful Duramax 3.0L Turbo-Diesel I6, producing 305 horsepower and an impressive 495 lb-ft of torque. Paired with a 10-speed automatic transmission with Electronic Precision Shift, this powertrain delivers smooth power delivery, strong towing capability, and excellent highway efficiency.
With tow/haul mode, powertrain grade braking, and cruise grade braking, the Sierra AT4 is built to confidently handle trailers, boats, and heavy loads across Ontario.
Additional capability features include:
• Engine block heater for Canadian winters • 220-amp alternator • 3.23 rear axle ratio • All-terrain tires for off-road confidence
🏔 AT4 Off-Road Capability
The Sierra AT4 is designed for drivers who want real off-road capability without sacrificing premium comfort.
This truck features:
• AT4 off-road suspension • All-terrain tires • High-clearance off-road steps • Bold AT4 exterior styling • Protective skid plates and off-road capability
Whether heading to the cottage, towing a trailer, or exploring trails, the AT4 is ready.
🖤 Premium AT4 Interior
Inside, the Sierra AT4 combines rugged character with upscale comfort. The Jet Black interior with Kalahari accents and perforated leather seating create a distinctive premium cabin that reflects the AT4’s adventurous personality.
The spacious Crew Cab provides excellent room for passengers and gear, making it perfect for both work and family life.
🧠 Advanced Technology Package
This Sierra AT4 is equipped with GMC’s Technology Package, bringing advanced driver information and visibility to every drive.
Highlights include:
• 15" Multicolour Head-Up Display • Rear Camera Mirror with full camera display • Bed View Camera for monitoring cargo or trailers • Trailer camera provisions for additional towing visibility
These systems provide incredible awareness whether towing, parking, or navigating tight spaces.
📱 GMC Premium Infotainment
The 13.4" GMC Premium Infotainment System with Google Built-In serves as the technology hub of the Sierra.
Features include:
• Google Maps navigation and voice assistant • Wireless Apple CarPlay & Android Auto • Bluetooth streaming audio • Large multi-touch display • Custom driver profiles
Everything is designed to keep you connected while maintaining focus on the road.
🌤 Premium Comfort & Convenience
This Sierra AT4 also includes several premium upgrades designed to enhance everyday driving.
Features include:
• Power sunroof • Rear sliding power window with defogger • Universal Home Remote • Hard folding truck bed cover • Sport step running boards • 3 Years of SiriusXM
Together these features make the Sierra AT4 equally comfortable for workdays and weekend road trips.
Why Buy Your GMC Sierra AT4 at Boyer Chevrolet Buick GMC Ajax?
At Boyer Chevrolet Buick GMC Ajax, located at 425 Bayly Street West, we proudly maintain a 4.7-star Google rating with over 1,500 customer reviews. Our team is committed to delivering a transparent, professional, and enjoyable buying experience.
When you choose Boyer Ajax, you receive:
• Competitive lease and finance options • A trusted GMC dealership serving Ajax, Whitby, Oshawa, and Durham Region • Factory-trained technicians and full service support • A dealership focused on long-term customer relationships
🚗 Book Your Test Drive Today
If you're considering trucks like the Ford F-150 Tremor, Ram Rebel, or Toyota Tundra TRD Pro, the 2026 GMC Sierra AT4 Duramax deserves a serious look.
📞 Call 905-427-2500 📍 Visit Boyer Chevrolet Buick GMC Ajax 📅 Book your test drive today
Packages & Options
Standard Equipment
Technical Specifications
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AM/FM Stereo
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Auxiliary Audio Input
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Bluetooth Connection
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MP3 Player
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Navigation System
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Smart Device Integration
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Requires Subscription
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Satellite Radio
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Premium Sound System
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Steering Wheel Audio Controls
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WiFi Hotspot
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Aluminum Wheels
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Tires - Front All-Terrain
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Tires - Rear All-Terrain
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Conventional Spare Tire
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Wheel, 17" x 8" (43.2 cm x 20.3 cm) full-size, steel spare
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Wheelhouse liners, rear (Deleted with (PCP) AT4 CarbonPro Edition.)
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Bumper, front, body-colour lower
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Bumper, rear body-colour with corner steps
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Grille (Black chrome header and grille insert bars with gloss black accents.)
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Daytime Running Lights
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LED Headlights
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Automatic Highbeams
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Fog Lamps
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Lighting, perimeter
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Taillamps, LED LED signature taillight with LED stop, turn & reverse and Fade-on/Fade-off animation
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Heated Mirrors
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Mirror Memory
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Power Folding Mirrors
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Power Mirror(s)
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Mirror caps, high gloss Black
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Intermittent Wipers
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Rain Sensing Wipers
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Variable Speed Intermittent Wipers
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Privacy Glass
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Lamps, cargo area, cab mounted integrated with centre high mount stop lamp, with switch in bank on left side of steering wheel
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LED Cargo Area Lighting located in cargo bed activated with switch on centre switch bank or key fob
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Integrated Tailgate Step
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Tailgate, gate function manual with EZ Lift includes power lock and release, includes hitch area light
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Tailgate and bed rail protection caps, top
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Door handles, body-colour
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Bed Liner
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Bucket Seats
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Leather Seats
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Driver Adjustable Lumbar
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Power Driver Seat
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Passenger Adjustable Lumbar
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Power Passenger Seat
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Heated Front Seat(s)
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Mirror Memory
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Seat Memory
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Cooled Front Seat(s)
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Pass-Through Rear Seat
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Rear Bench Seat
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Heated Rear Seat(s)
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Centre Console, floor-mounted with cup holders, cell phone storage, power cord management, hanging file folder capability
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Floor covering, colour-keyed carpeting
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Floor Mats
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Adjustable Steering Wheel
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Steering wheel, wrapped
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Heated Steering Wheel
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Driver Information Centre, enhanced, 12.3" diagonal reconfigurable multicolour digital display
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GMC Premium information Display-13.4" diagonal Multicolour I touch screen
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In-Vehicle Trailering App, System includes checklist, trailer maintenance reminders, trailer security alerts, trailer mileage, tow/haul reminder, trailer electrical diagnostics and Trailer Tire Pressure Monitor System module
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Compass, located in instrument cluster
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Exterior Temperature Display, located in radio display
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Brake lining wear indicator
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Power Windows
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Power Door Locks
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Keyless Entry
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Keyless Start
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Remote Engine Start
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Adaptive Cruise Control
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Cruise Control
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Security System
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Steering column lock, electrical
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Wireless Charging
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Power outlet, interior power outlet, 120-volt (400 watts shared with (KC9) bed mounted power outlet)
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Power outlet, bed mounted, 120-volt (400 watts shared with (KI4) interior power outlet)
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Auxiliary Audio Input
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MP3 Player
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USB ports, (2) charge-only, rear
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A/C
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Climate Control
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Multi-Zone A/C
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Air vents, rear
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Rear Defrost
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Auto-Dimming Rearview Mirror
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Assist handles front A-pillar mounted for driver and passenger, rear B-pillar mounted
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Diesel Fuel
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Straight 6 Cylinder Engine
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Turbocharged
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10-Speed A/T
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A/T
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Transmission w/Dual Shift Mode
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Rear axle, 3.23 ratio
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Pickup bed
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GVWR, 7200 lbs. (3266 kg) (Requires TK10*43 Crew Cab 4WD model with (LZ0) Duramax 3.0L Turbo-Diesel I6 engine.)
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Keyless Start
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Air filter, heavy-duty
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Automatic Stop/Start
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Hill Descent Control
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Locking/Limited Slip Differential
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Transfer case, two-speed, electronic Autotrac with push button control (4WD models only)
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Suspension, Off-Road with 2" factory installed lift and monotube shocks
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Four Wheel Drive
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Alternator, 220 amps
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Battery, heavy-duty 850 cold-cranking amps/95 Amp-hr, maintenance-free with rundown protection and retained accessory power (Included and only available with (LZ0) Duramax 3.0L Turbo-Diesel I6 engine.)
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Frame, fully-boxed, hydroformed front section
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Trailer brake controller, integrated
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Tow Hooks
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Skid Plates
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Cargo tie downs (12), fixed, rated at 500 lbs per corner
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Power Steering
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4-Wheel Disc Brakes
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ABS
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Exhaust, dual system (Includes chrome exhaust tips. Not available with (L87) 6.2L EcoTec3 V8 engine.)
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Exhaust, aluminized stainless-steel muffler and tailpipe
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Tow Hitch
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Automatic Highbeams
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Front Collision Mitigation
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Front Collision Warning
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Lane Departure Warning
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Lane Keeping Assist
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Front Collision Mitigation
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Front Collision Warning
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Stability Control
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Traction Control
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Daytime Running Lights
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Driver Air Bag
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Front Head Air Bag
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Front Side Air Bag
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Passenger Air Bag
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Passenger Air Bag Sensor
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Rear Head Air Bag
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Requires Subscription
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Telematics
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Hitch View with image adjustment, Pan/Zoom/Tilt
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Hitch Guidance
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Aerial View Display System
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Back-Up Camera
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Trailer Camera Provisions and trailer viewing software
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Rear Parking Aid
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Following Distance Indicator (Included and only available with (PDI) GMC Pro Safety.)
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Lane Departure Warning
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Lane Keeping Assist
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Blind Spot Monitor
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Cross-Traffic Alert
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Rear Pedestrian Alert
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Driver Monitoring
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Seat Belt Adjustable Guide Loops, front row only
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Rear Seat Belt Indicator
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Buckle to Drive prevents vehicle from being shifted out of Park until driver seat belt is fastened; times out after 20 seconds and encourages seat belt use (Included and only available with (PDI) GMC Pro Safety.)
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Tire Pressure Monitor
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Rear Seat Reminder
No matches were found.
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Vehicle NameGMC Sierra 1500
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Body StyleCrew Cab Pickup
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Body CodeE63
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DrivetrainFour Wheel Drive
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Trans Order CodeMQC
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Trans Type10
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Trans Description Cont.Automatic
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First Gear Ratio (:1)4.70
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Second Gear Ratio (:1)2.99
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Third Gear Ratio (:1)2.15
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Fourth Gear Ratio (:1)1.77
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Fifth Gear Ratio (:1)1.52
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Sixth Gear Ratio (:1)1.28
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Seventh Gear Ratio (:1)1.00
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Eighth Gear Ratio (:1)0.85
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Ninth Gear Ratio (:1)0.69
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Tenth Gear Ratio (:1)0.64
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Reverse Ratio (:1)4.87
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Transfer Case ModelMagna MP3023/4
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Transfer Case Gear Ratio (:1), High1.00
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Transfer Case Gear Ratio (:1), Low2.69
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Passenger Capacity5
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Front Head Room (in)43.03
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Front Leg Room (in)44.53
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Front Shoulder Room (in)64.54
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Front Hip Room (in)60.78
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Second Head Room (in)40.12
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Second Leg Room (in)43.4
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Second Shoulder Room (in)64
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Second Hip Room (in)59.24
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Gross Axle Wt Rating - Front (lbs)3800
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Gross Axle Wt Rating - Rear (lbs)3800
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Curb Weight - Front (lbs)2845
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Curb Weight - Rear (lbs)1981
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Gross Vehicle Weight Rating Cap (lbs)7200
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Gross Combined Wt Rating (lbs)15000
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EnerGuide Estimate - City (L/100 km)10.7
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EnerGuide Estimate - Hwy (L/100 km)9.3
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G/km Of CO2 Emissions270
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Dead Weight Hitch - Max Trailer Wt. (lbs)5000
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Dead Weight Hitch - Max Tongue Wt. (lbs)500
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Wt Distributing Hitch - Max Trailer Wt. (lbs)8700
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Wt Distributing Hitch - Max Tongue Wt. (lbs)870
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Fifth Wheel Hitch - Max Trailer Wt. (lbs)6700
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Fifth Wheel Hitch - Max Tongue Wt. (lbs)1675
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Maximum Trailering Capacity (lbs)9000
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Engine TypeTurbocharged Diesel I6
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Fuel SystemDirect Injection
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Engine Order CodeLZ0
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Displacement3.0L/183
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SAE Net Horsepower @ RPM305 @ 3750
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SAE Net Torque @ RPM495 @ 2750
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Cold Cranking Amps @ 0° F (Primary)850
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Maximum Alternator Capacity (amps)220
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Frame TypeHydroformed
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Suspension Type - FrontIndependent
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Suspension Type - RearSolid Axle
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Spring Capacity - Front (lbs)3800
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Spring Capacity - Rear (lbs)3850
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Axle Capacity - Front (lbs)3800
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Axle Capacity - Rear (lbs)3800
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Axle Ratio (:1) - Front3.23
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Axle Ratio (:1) - Rear3.23
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Stabilizer Bar Diameter - Front (in)1.3
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Front Tire Order CodeQAE
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Rear Tire Order CodeQAE
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Spare Tire Order CodeQAQ
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Front Tire Size275/60R20SL
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Rear Tire Size275/60R20SL
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Spare Tire Size255/80R17SL
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Front Tire Capacity (lbs)3800
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Rear Tire Capacity (lbs)3800
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Revolutions/Mile @ 45 mph - Front (Rev/Mile)N/A
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Revolutions/Mile @ 45 mph - Rear (Rev/Mile)N/A
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Revolutions/Mile @ 45 mph - Spare (Rev/Mile)N/A
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Front Wheel Size (in)20 x 9
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Rear Wheel Size (in)20 x 9
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Spare Wheel Size (in)17 x 8
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Front Wheel MaterialAluminum
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Rear Wheel MaterialAluminum
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Spare Wheel MaterialSteel
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Steering TypeElectric Rack & Pinion
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Turning Diameter - Curb to Curb (ft)47.3
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Turning Diameter - Wall to Wall (ft)N/A
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Brake TypePwr
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Brake ABS System4-Wheel
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Disc - FrontYes
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Disc - RearYes
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Front Brake Rotor Diam x Thickness (in)13 x 1.18
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Rear Brake Rotor Diam x Thickness (in)13.6 x 0.79
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Fuel Tank Capacity, Approx (L)91
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Wheelbase (in)148
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Length, Overall (in)232.9
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Width, Max w/o mirrors (in)81.24
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Height, Overall (in)78.35
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Ground Clearance, Front (in)11.1
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Ground Clearance, Rear (in)11.1
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Cargo Box Length @ Floor (in)69.92
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Cargo Box Width @ Floor (in)71.4
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Cargo Box Width @ Wheelhousings (in)50.63
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Cargo Box (Area) Height (in)22.42
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Cargo Volume (ft³)62.9
No matches were found.
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* Plus HST & Licensing. Price includes: Dealer Admin Fee ($599), Etching ($299), Tire Protection ($199), Tire Duty ($22.50), and OMVIC fee ($22.00) Every reasonable effort is made to ensure the accuracy of the information listed above. Vehicle pricing, incentives, options (including standard equipment), and technical specifications listed is for the 2026 GMC Sierra 1500 AT4 may not match the exact vehicle displayed. Please confirm the accuracy of this information with a sales representative.