Vehicle Details
Body Style
Truck
Engine
6.6L 8Cyl
Exterior Colour
White
Interior Colour
Black
Transmission
Automatic
Drivetrain
4×4
Stock #
302556
Trim Details
Crew Cab Standard Box 4-Wheel Drive AT4
The 2026 GMC Sierra 2500HD AT4 is built for those who demand extreme capability without sacrificing comfort or technology. Combining heavy-duty Duramax® diesel power, factory-installed off-road hardware, and premium AT4 design, this truck is engineered to dominate tough jobs, remote terrain, and long hauls with confidence and control.Â
Performance & Heavy-Duty CapabilityÂ
Engine: Duramax® 6.6L V8 Turbo Diesel delivering exceptional torque and relentless towing strengthÂ
Transmission: Heavy-duty 10-speed automatic transmission designed for smooth, confident power delivery under loadÂ
Drivetrain: Autotrac two-speed 4-Wheel Drive system for confident traction on rugged terrain and in severe weatherÂ
Rear Axle Ratio: 3.42 rear axle optimized for towing, hauling, and overall durabilityÂ
Integrated exhaust brake for enhanced downhill control and reduced brake wearÂ
Automatic locking rear differential to maintain traction in low-grip conditionsÂ
Trailering Equipment with integrated trailer brake controller, Hitch View, and advanced trailering technologiesÂ
Gooseneck and 5th-wheel prep for serious towing capabilityÂ
AT4 Off-Road ReadinessÂ
AT4 off-road suspension engineered for durability and improved ground clearanceÂ
Skid plates protecting critical underbody componentsÂ
Hill Descent Control for steady, controlled descents on steep or uneven terrainÂ
Red front recovery hooks delivering both functionality and signature AT4 stylingÂ
20" black aluminum wheels wrapped in all-terrain tires for confident grip on and off the pavementÂ
Off-road high-clearance assist steps for easier access in challenging environmentsÂ
Interior Comfort & ConvenienceÂ
Jet Black and Kalahari interior combining rugged character with premium craftsmanshipÂ
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 vents for balanced cabin temperaturesÂ
Power sliding rear window and rear seat storage package for added versatilityÂ
Wireless charging pad and multiple USB and 120V power outlets to support work and travel needsÂ
Remote start system to pre-warm or cool the cabin before you step insideÂ
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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 information directly 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
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Safety & Driver AssistanceÂ
Sierra HD Pro Safety technologies designed to support 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
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Exterior Styling & UtilityÂ
AT4-exclusive exterior design with dark accents and aggressive detailingÂ
Summit White exterior finish for a clean, bold, and commanding 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 durability and protectionÂ
EZ Lift power tailgate with power lock and releaseÂ
Perimeter and task lighting to illuminate worksites, campsites, and trailsÂ
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Whether you’re hauling heavy equipment, towing large trailers, or pushing beyond the pavement, the 2026 GMC Sierra 2500HD AT4 delivers uncompromising diesel power, advanced technology, and authentic off-road capability. It’s a heavy-duty truck built to handle the toughest challenges—while keeping you comfortable, confident, and firmly in 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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