2026 GMC Sierra 3500 AT4

The Sierra 3500 is GMC's heavy-duty pickup, built to tow and haul with serious capability across its trim range. It competes head-to-head with the Ford F-350 Super Duty and Ram 3500 in the heavy-duty truck segment. The Sierra 3500 drives with the commanding presence you expect from a heavy-duty truck, and the diesel provides strong low-end grunt for towing. Cabin space is generous, with available luxury trims like Denali adding upscale materials and tech features. The AT4 is the off-road-oriented Sierra 3500, sitting above the SLT and below the Denali in GMC's heavy-duty lineup. Under the hood is the Duramax 6.6L Turbo-Diesel paired with a ten-speed automatic and four-wheel drive, giving you strong low-end torque for towing. It rides on an off-road suspension with twin-tube Rancho shocks and skid plates, so expect a firmer feel on pavement in exchange for serious trail capability.