2026 GMC Sierra 3500 HD SRW AT4 Duramax Diesel SWB

Heavy-Duty Power. Off-Road Confidence. Canadian Proven.

The 2026 GMC Sierra 3500 HD SRW AT4 is built for those who refuse to compromise—delivering the payload and towing capacity of a heavy-duty truck with the off-road capability and premium refinement that the AT4 trim is known for. Powered by the legendary Duramax 6.6L Turbo-Diesel V8 and configured as a Single Rear Wheel (SRW) with a Short Wheelbase (SWB), this truck is engineered to handle Canada’s toughest job sites, longest hauls, and harshest winter conditions—all while keeping you comfortable, connected, and in command.

Unstoppable Powertrain

At the heart of this Sierra 3500 HD lies the Duramax 6.6L Turbo-Diesel V8, delivering a staggering 975 lb-ft of torque and class-leading horsepower. Paired with the proven Allison® 10-speed automatic transmission, this combination provides smooth, confident power delivery whether you’re merging onto the highway with a loaded trailer or navigating steep mountain grades. The available exhaust brake reduces wear on your service brakes during long descents, giving you greater control when towing heavy loads.

The Single Rear Wheel (SRW) configuration strikes the ideal balance between maximum towing capacity and everyday drivability. You get the stability and payload required for fifth-wheel trailers, heavy equipment, or commercial use, combined with a footprint that handles snow-covered streets and tight parking lots with ease.

Short Wheel Base Maneuverability

The Short Wheel Base (SWB) design offers a distinct advantage in real-world conditions. A tighter turning radius makes maneuvering through job sites, downtown cores, and busy campsites noticeably easier than long-bed alternatives. You gain heavy-duty capability without sacrificing the agility needed for daily driving—a combination that Canadian truck owners consistently value.

AT4 Trim: Built for the Elements

The AT4 is the ultimate expression of GMC’s off-road-focused heavy-duty lineup, featuring a factory-installed 2-inch suspension lift that provides increased ground clearance for tackling uneven terrain, deep snow, and rutted work sites. Rancho® monotube shocks are tuned to absorb harsh impacts while maintaining composure under heavy loads, and heavy-duty aluminum skid plates protect the front underbody, steering, and transfer case when the pavement ends.

The standard four-wheel-drive system includes an auto-lock rear differential and an Auto mode that seamlessly shifts between 2WD and 4WD based on road conditions—an essential feature for Canadian winters where highways can transition from dry pavement to ice-covered asphalt in minutes.

Purpose-Built for Canadian Winters

GMC engineers designed this truck with cold-weather resilience in mind. The AT4 comes equipped with:

• Heated steering wheel and heated front seats

• Heated rear outboard seats for passenger comfort

• Remote start to warm the cabin before you step outside

• Engine block heater for reliable starts on the coldest mornings

• Heavy-duty windshield wipers de-icer

The aggressive all-terrain tires mounted on 20-inch machined aluminum wheels provide confident traction in mud, gravel, and snow, while the high-gloss black accents and body-color grille give the AT4 its signature bold appearance.

Premium Interior with Advanced Technology

Inside, the Sierra 3500 HD AT4 offers a sanctuary of premium materials and cutting-edge technology. Leather-appointed seating features distinctive Kalahari accents, while authentic open-pore wood trim adds a refined touch that sets the AT4 apart from standard heavy-duty trucks.

The cockpit is dominated by a 13.4-inch diagonal touchscreen infotainment system with wireless Apple CarPlay® and Android Auto™, paired with a 12.3-inch diagonal digital driver information center that provides customizable vehicle data, towing information, and off-road metrics. A 15-camera view system—including transparent trailer view and hitch guidance—makes hitching up a fifth-wheel or gooseneck trailer a straightforward process, even when working alone.

Advanced Trailering Technology

GMC’s Advanced Trailering System takes the guesswork out of towing. Key features include:

• Transparent Trailer View: See through your trailer via the camera system for easier maneuvering

• Trailer Length Indicator: Visual guidance for lane changes and backing

• Jackknife Alert: Audible and visual warnings to prevent trailer collisions

• Trailer Tire Pressure Monitoring: Direct monitoring of trailer tire pressures from the driver’s seat

Why This Configuration Matters

The combination of the 3500 HD platform, Single Rear Wheel layout, and Short Wheel Base makes this specific Sierra a versatile choice for Canadian truck buyers. You get the full heavy-duty capability required for commercial applications, large RVs, or horse trailers, but in a package that handles daily driving duties without the compromises associated with dual rear wheels or long-bed configurations.

Whether you’re towing a skid steer to a job site, hauling a holiday trailer to the Rockies, or navigating a winter storm on the Trans-Canada Highway, this truck delivers the capability, comfort, and confidence you demand.

Key Specifications

FeatureDetailsEngine6.6L Duramax Turbo-Diesel V8TransmissionAllison® 10-Speed AutomaticTorque975 lb-ftConfiguration3500 HD, Single Rear Wheel, Short Wheel BaseDrivetrain4WD with Auto-Trac Transfer Case Suspension Factory 2-Inch Lift with Rancho® Monotube ShocksWheels20" Machined Aluminum with High-Gloss Black AccentsInfotainment13.4" Touchscreen with Wireless Apple CarPlay® & Android Auto ™Interior Leather-Appointed Seating, Heated/Ventilated Front Seats, Heated Rear Seats, Heated Steering WheelTrailering15-Camera System, Transparent Trailer View, Hitch Guidance Cold Weather Engine Block Heater, Remote Start, Windshield De-Icer

VSA 10374