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2026 GMC Sierra 2500HD AT4
Vehicle Details
Body Style
Truck
Engine
6.6L 8Cyl
Exterior Colour
Silver
Interior Colour
Black
Transmission
Automatic
Drivetrain
4×4
Stock #
302555
Trim Details
Crew Cab Standard Box 4-Wheel Drive AT4
The 2026 GMC Sierra 2500HD AT4 is engineered for extreme capability and premium comfort, blending heavy-duty strength with refined off-road confidence. With its aggressive AT4 stance, darkened accents, and purpose-built hardware, this truck is designed for those who demand uncompromising performance on the jobsite, the trail, or the open highway.Â
Performance & Heavy-Duty CapabilityÂ
Engine: Duramax® 6.6L V8 Turbo Diesel delivering massive torque and relentless pulling powerÂ
Transmission: 10-speed Allison® automatic transmission engineered for smooth shifts under heavy loadsÂ
Drivetrain: Autotrac two-speed 4-Wheel Drive system for confident traction on rough terrain and in harsh conditionsÂ
Rear Axle Ratio: 3.42 rear axle optimized for towing and heavy haulingÂ
Automatic locking rear differential for enhanced traction when conditions demand itÂ
Integrated exhaust brake to improve downhill control and reduce brake wearÂ
Trailering Equipment Package with integrated trailer brake controller, Hitch View, and advanced trailering technologiesÂ
Gooseneck and 5th-wheel prep for serious towing capabilityÂ
GVWR rated for heavy-duty work and demanding payloadsÂ
AT4 Off-Road ConfidenceÂ
AT4 off-road suspension tuned for rugged terrain and improved ground clearanceÂ
Skid plates protecting key underbody componentsÂ
Hill Descent Control for controlled descents on steep or uneven surfacesÂ
Red front recovery hooks adding both function and signature AT4 stylingÂ
All-terrain tires mounted on bold 20" black aluminum wheelsÂ
Off-road high-clearance assist steps for confident entry and exitÂ
Interior Comfort & Premium AppointmentsÂ
Jet Black and Kalahari interior with premium materials and refined detailingÂ
Heated and ventilated front seats for year-round comfortÂ
Heated rear outboard seats and heated steering wheel for cold-weather drivingÂ
Power-adjustable front seats with memory settings for personalized comfortÂ
Dual-zone automatic climate control with rear air ventsÂ
Power sliding rear window and rear seat storage package for added versatilityÂ
Wireless charging pad and multiple USB and 120V power outlets for work and travel needsÂ
Advanced Technology & ConnectivityÂ
13.4" GMC Premium Infotainment touchscreen with Google built-in and navigation capabilityÂ
Wireless Apple CarPlay® and Android Autoâ„¢ for seamless smartphone integrationÂ
12" reconfigurable digital driver information displayÂ
Multicolor head-up display projecting key driving information onto the windshieldÂ
Bose® premium audio system delivering rich, immersive soundÂ
HD Surround Vision and Bed View Camera for enhanced visibility when maneuvering or traileringÂ
Safety & Driver AssistanceÂ
Sierra HD Pro Safety technologies for enhanced driver awareness and confidenceÂ
Forward Collision Alert with Automatic Emergency BrakingÂ
Lane Departure Warning and Following Distance IndicatorÂ
Front and Rear Park Assist for easier maneuvering in tight spacesÂ
Trailer Side Blind Zone Alert and Rear Cross Traffic AlertÂ
Teen Driver Mode and Buckle-to-Drive for added safety awarenessÂ
Exterior Styling & UtilityÂ
AT4-exclusive exterior with dark accents and rugged detailingÂ
Sterling Metallic exterior finish with bold, premium presenceÂ
LED headlamps, fog lamps, cargo bed lighting, and roof marker lamps for maximum visibilityÂ
GMC MultiProâ„¢ Tailgate offering multiple configurations for loading, stepping, and workingÂ
Spray-on bedliner for long-lasting durabilityÂ
EZ Lift power tailgate with power lock and releaseÂ
Perimeter and task lighting to illuminate worksites and campsites alikeÂ
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Whether hauling heavy equipment, towing a large trailer, or exploring off the beaten path, the 2026 GMC Sierra 2500HD AT4 delivers unmatched diesel power, advanced technology, and premium off-road capability. It’s a heavy-duty truck built to conquer demanding terrain while keeping you comfortable, confident, and in complete control.Â
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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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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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Tire carrier lock keyed cylinder lock that utilizes same key as ignition and door
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Bumper, front, body-colour lower
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Bed Liner
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CornerStep, rear bumper
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Cargo tie downs (12), fixed, rated at 500 lbs (226.8 kg) per corner
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Grille (Gloss Black header and grille insert bars with Black Chrome accents.)
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Daytime Running Lights
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Automatic Highbeams
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Fog Lamps
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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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Taillamps, Animated LED Signature Tail, Stop, turn and Reverse lamps
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Heated Mirrors
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Integrated Turn Signal Mirrors
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Power Folding Mirrors
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Power Mirror(s)
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Privacy Glass
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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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Door handles, body-colour
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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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Bucket Seats
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Leather Seats
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Pass-Through Rear Seat
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Rear Bench Seat
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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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Cooled Front Seat(s)
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Heated Rear Seat(s)
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Mirror Memory
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Seat Memory
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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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Steering wheel, wrapped
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Heated Steering Wheel
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Steering Wheel Audio Controls
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Adjustable Steering Wheel
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Driver Information Centre, enhanced, 12.3" diagonal reconfigurable multicolour digital display
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Rear Seat Reminder
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GMC Premium information Display- 13.4" diagonal Multicolour touch screen
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Exterior Temperature Display, located in radio display
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Compass, located in instrument cluster
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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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Wireless Charging
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Security System
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Power outlet, instrument panel, 120-volt (400 watts shared with (KC9) bed mounted power outlet)
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Auxiliary Audio Input
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MP3 Player
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Air vents, 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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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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8 Cylinder Engine
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Gasoline Fuel
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10-Speed A/T
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A/T
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Rear axle, 3.73 ratio (Requires (L8T) 6.6L V8 gas engine.)
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Running Boards/Side Steps
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GVWR, 10,850 lbs. (4921 kg) (Included and only available with TK20743 model and (L8T) 6.6L V8 gas engine with 18", 20" or 22" wheels.)
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Keyless Start
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Hill Descent Control
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Transfer case, two-speed active, electronic Autotrac with push button control
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Locking/Limited Slip Differential
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Four Wheel Drive
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Cooling, external engine oil cooler
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Cooling, auxiliary external transmission oil cooler
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Air filter, heavy-duty
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Air filtration monitoring
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Battery, heavy-duty 720 cold-cranking amps/80 Amp-hr maintenance-free with rundown protection and retained accessory power (Included and only available with (L8T) 6.6L V8 gas engine.)
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Alternator, 170 amps (Requires (L8T) 6.6L V8 gas engine.)
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Trailer brake controller, integrated
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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 (Includes trailer tire pressure monitoring alert when (PTT) trailer tire pressure monitor sensors are installed.)
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Tow Hooks
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Skid Plates protect the oil pan, front axle and transfer case
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Frame, fully-boxed, hydroformed front section and a fully-boxed stamped rear section
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Suspension, Off-Road includes twin-tube shocks
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Power Steering
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4-Wheel Disc Brakes
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ABS
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Brake lining wear indicator
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Capless Fuel Fill (Requires (L8T) 6.6L gas V8 engine.)
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X31 Off-Road Package includes (JHD) Hill Descent Control, (NZZ) skid plates, Off-Road suspension and Twin-tube Rancho shocks
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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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Tow Hitch
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ProGrade Trailering System includes (PZ8) Hitch Guidance with Hitch View and (UET) In-vehicle Trailering App
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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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Rear Parking Aid
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Aerial View Display System
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Back-Up Camera
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Bed View Camera, camera in the CHMSL to show a view of the cargo bed display located in infotainment screen, includes Two Trailer Camera Provisions
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Hitch Guidance dynamic single line to aid in truck trailer alignment for hitching
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Following Distance Indicator (Included and only available with (PDI) Sierra HD Pro Safety.)
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Lane Departure Warning
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Cross-Traffic Alert
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Blind Spot Monitor
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Seat Belt Adjustable Guide Loops, front row only
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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) Sierra HD Pro Safety.)
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Safety Alert Seat
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Driver Restriction Features
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Tire Pressure Monitor
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Trailering Information Label provides max trailer ratings for tongue weight, conventional, gooseneck and 5th wheel trailering
No matches were found.
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Vehicle NameGMC Sierra 2500HD
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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 CodeMGM
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Trans Type10
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Trans Description Cont.Automatic
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First Gear Ratio (:1)4.54
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Second Gear Ratio (:1)2.87
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Third Gear Ratio (:1)2.06
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Fourth Gear Ratio (:1)1.72
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Fifth Gear Ratio (:1)1.48
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Sixth Gear Ratio (:1)1.26
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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)0.63
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Reverse Ratio (:1)4.54
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Clutch Size (in)N/A
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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)66.02
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Front Hip Room (in)61.18
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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)65.3
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Second Hip Room (in)60.24
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Curb Weight - Front (lbs)4023
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Curb Weight - Rear (lbs)2822
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Gross Vehicle Weight Rating Cap (lbs)11350
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Gross Combined Wt Rating (lbs)27500
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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)18500
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Wt Distributing Hitch - Max Tongue Wt. (lbs)1850
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Fifth Wheel Hitch - Max Trailer Wt. (lbs)17300
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Fifth Wheel Hitch - Max Tongue Wt. (lbs)4325
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Maximum Trailering Capacity (lbs)20000
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Engine Order CodeL5P
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Engine TypeTurbocharged Diesel V8
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Displacement6.6L
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Fuel SystemDirect Injection
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SAE Net Horsepower @ RPM470 @ 2800
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SAE Net Torque @ RPM975 @ 1600
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Cold Cranking Amps @ 0° F (Primary)720
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Maximum Alternator Capacity (amps)220
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Maximum Alternator WattsN/A
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Suspension Type - FrontShort/Long Arm
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Suspension Type - RearMulti-Leaf Springs
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Axle Ratio (:1) - Front3.42
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Axle Ratio (:1) - Rear3.42
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Shock Absorber Diameter - Front (mm)2.01
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Shock Absorber Diameter - Rear (mm)2.01
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Stabilizer Bar Diameter - Front (in)1.38
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Front Tire Order CodeQF9
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Rear Tire Order CodeQF9
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Spare Tire Order CodeZYG
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Front Tire SizeLT275/65R20
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Rear Tire SizeLT275/65R20
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Spare Tire SizeLT275/70R18
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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
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Rear Wheel Size (in)20
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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 TypePwr Recirculating Ball
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Turning Diameter - Curb to Curb (ft)52.7
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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)14 x 1.6
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Rear Brake Rotor Diam x Thickness (in)14.1 x 1.3
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Fuel Tank Capacity, Approx (L)136
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Wheelbase (in)159
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Length, Overall (in)250.75
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Width, Max w/o mirrors (in)81.85
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Height, Overall (in)79.82
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Cab to Axle (in)42.17
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Ground Clearance, Front (in)10.12
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Ground Clearance, Rear (in)10.12
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Cargo Box Length @ Floor (in)82.2
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Cargo Box Width @ Floor (in)71.4
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Cargo Box Width @ Wheelhousings (in)51.85
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Cargo Box (Area) Height (in)21
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Cargo Volume (ft³)69.5
No matches were found.
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* 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 2500HD AT4 may not match the exact vehicle displayed. Please confirm the accuracy of this information with a sales representative.