2026 GMC Sierra 3500HD Crew Cab AT4 Duramax 4x4

Off-Road Authority. Heavy-Duty Capability.

Introducing the 2026 GMC Sierra 3500HD AT4—where serious off-road readiness meets uncompromised heavy-duty capability. Now available at our dealership, the AT4 trim is built for those who need to venture beyond the pavement without leaving their work behind. With the legendary Duramax diesel engine, off-road-tuned suspension, and rugged good looks, this truck is ready for the toughest Canadian terrain .

Duramax Power: The Heart of a Workhorse

Under the hood beats GMC's legendary Duramax 6.6L Turbo-Diesel V8 engine, delivering a commanding 470 horsepower and a massive 975 lb-ft of torque . This B20-diesel compatible powerhouse provides the grunt you need for the most demanding jobs, from hauling heavy equipment to towing large fifth-wheel campers across the province .

The Duramax pairs with a 10-speed automatic Allison transmission, delivering smooth, confident shifts whether you're pulling away from a stoplight or climbing a steep grade with a heavy load . The standard exhaust brake helps improve control when towing, reducing brake wear and providing peace of mind on downhill grades .

Serious Capability: Built for the Toughest Jobs

The Sierra 3500HD AT4 is engineered for those who demand maximum capability:

• Maximum conventional towing: 20,000 lbs when properly equipped

• Maximum gooseneck/fifth-wheel towing: 21,300 lbs

• Maximum payload: 4,127 lbs

• 11.1 inches of ground clearance for off-road confidence

• Auto-locking rear differential for enhanced traction in slippery conditions

• Integrated trailer brake controller for confident, precise trailer control

• Skid plates protect the oil pan, front axle, and transfer case

The 4x4 system features a two-speed electronic Autotrac transfer case with push-button control, giving you confidence in everything from muddy job sites to snow-covered highways . Hill Descent Control helps maintain control on steep, off-road descents .

AT4 Off-Road Readiness: Built for Adventure

The AT4 trim stands apart with genuine off-road credentials:

• Off-Road Suspension Package with twin-tube Rancho® shocks

• 20" gloss-black aluminum wheels with available all-terrain tires

• Red recovery hooks front and rear

• Unique AT4 grille with gloss black inserts and bold styling

• Skid plates protecting vital components underneath

• Digital Variable Steering Assist automatically adjusts steering based on speed and road conditions, reducing driver effort and fatigue on long journeys

AT4 Interior: Rugged Premium Comfort

Step inside the AT4 cabin, and you'll discover a space designed for both adventure and comfort:

• Jet Black interior with Kalahari accents—exclusive to AT4 trim

• Perforated leather-appointed front seats with heating and ventilation for year-round comfort

• Heated second-row outboard seats ensuring passenger comfort on long journeys

• Heated, leather-wrapped steering wheel for cold Canadian mornings

• Dual-zone automatic climate control with individual settings

• 10-way power driver and passenger seats with lumbar adjustment

• Remote Start standard—warm up your truck before stepping outside

The Crew Cab configuration offers generous passenger space, with 43.4 inches of rear legroom ensuring even tall passengers travel in comfort .

Technology: The Ultimate Command Centre

The Sierra 3500HD AT4 sets new standards for connectivity with its advanced technology suite:

• 13.4-inch diagonal Premium GMC Infotainment System with Google built-in, featuring natural voice assistance and navigation

• 12.3-inch diagonal reconfigurable digital Driver Information Centre displaying key driving data right in your line of sight

• Bose Premium 7-speaker sound system with Richbass woofer for immersive audio

• Wireless Apple CarPlay and Android Auto—no cables required

• Wireless charging pad for compatible devices

• Built-in 5G Wi-Fi Hotspot capable keeping everyone connected

• Multiple USB ports throughout the cabin

Available 15-inch multicolour Head-Up Display projects essential information onto the windshield .

MultiPro Tailgate: Six Functions, Infinite Possibilities

The revolutionary GMC MultiPro Tailgate offers six functional load/access features—from a full-width step to a mobile workstation and easy bed loading . The spray-on bedliner with GMC logo provides durable cargo protection .

In-Vehicle Trailering App: Your Intelligent Towing Partner

For those who tow, the Sierra AT4 includes the sophisticated In-Vehicle Trailering App:

• Pre-departure checklist to ensure everything is connected properly

• Trailer maintenance reminders and security alerts

• Real-time trailer mileage tracking

• Electrical diagnostics and Trailer Tire Pressure Monitor System capability

• Trailer Side Blind Zone Alert for confidence when changing lanes

• Hitch Guidance with Hitch View for easier trailer hookups

Up to 14 available camera views include Bed View, HD Surround Vision, and Trailer Camera Provisions .

Comprehensive Safety: GMC Pro Safety

Your peace of mind is paramount. The Sierra AT4 comes equipped with GMC Pro Safety:

• Enhanced Automatic Emergency Braking and Forward Collision Alert

• Front Pedestrian Braking for added urban protection

• Lane Keep Assist with Lane Departure Warning

• Following Distance Indicator and IntelliBeam auto high beams

• Safety Alert Seat that vibrates to warn the driver

• Buckle to Drive encourages seat belt use

Additional safety features include:

• HD Surround Vision providing an overhead view

• Front and Rear Park Assist with ultrasonic sensors

• Rear Cross Traffic Alert and Blind Spot Monitor

• Rear Seat Reminder to help prevent forgetting children or pets

• Trailer Sway Control and Hill Start Assist

Utility Features for Canadian Living

The Sierra AT4 is loaded with thoughtful features that make work and life easier:

• 120-volt power outlet in the bed (400 watts shared with interior outlet)

• LED cargo area lighting with convenient switch or key fob activation

• Engine block heater standard for those frigid Canadian mornings

• Heavy-duty battery with 720 cold-cranking amps

• Power-retractable assist steps with LED lighting for easy access

The Confidence of OnStar and Warranty Protection

Every new Sierra AT4 comes with OnStar Basics included for up to 8 years, providing mobile app commands, connectivity for select apps, navigation with real-time traffic, and Automatic Crash Response.

GMC's comprehensive warranty coverage includes:

• 36 Months / 60,000 km New Vehicle Limited Warranty

• 60 Months / 100,000 km Powertrain Warranty

• 60 Months / 100,000 km Roadside Assistance

• 72 Months / 160,000 km Corrosion Warranty

Experience the AT4 Difference

The 2026 GMC Sierra 3500HD Crew Cab AT4 SRW Duramax 4x4 is more than just a truck—it's a statement. It's for those who need to go where the road ends without sacrificing capability or comfort. With its legendary Duramax power, sophisticated technology, and thoughtful features, it's ready for whatever your work and adventure demand.

VSA 10374