2026 GMC Sierra HD AT4: Danvers Buyers Guide

Quick Answer: The 2026 Sierra HD AT4

AT4 starts at $72,200 MSRP plus a $2,795 destination charge and is the off-road-focused trim in the 2026 Sierra 2500 HD/3500 HD lineup. It gets an exclusive Jet Black interior with Kalahari accents on heated and ventilated perforated leather front seats, exclusive 20-inch gloss-black aluminum wheels with available BFGoodrich off-road tires, an Off-Road Suspension Package with twin-tube Rancho shocks and skid plates, up to 14 camera views with HD Surround Vision, and standard Adaptive Cruise Control with trailering. A 15-inch Head-Up Display with an off-road inclinometer and the Duramax 6.6L Turbo-Diesel are both available rather than standard.

An off-road trim that still has to tow 20,000 pounds

AT4 on the Sierra HD is a different proposition than AT4 on a smaller GMC. This is a heavy-duty truck with genuine gooseneck and fifth-wheel towing capability, so the Rancho shocks and skid plates have to work alongside serious trailering hardware rather than instead of it — which is exactly why Adaptive Cruise Control with trailering comes standard here, not as an upcharge like it is on SLE and SLT. The 14 available camera views with HD Surround Vision matter just as much backing up to a trailer hitch as they do picking a line over rocks, and the exclusive interior and 20-inch wheel package set AT4 apart visually from SLT without pushing all the way to Denali pricing.

One trap worth knowing before configuring: unlike the light-duty Sierra 1500, where AT4 comes standard with the diesel, the Sierra HD's AT4 runs the standard 6.6L V8 gas engine (401 hp, 464 lb-ft) with the Duramax 6.6L Turbo-Diesel as an available upgrade — the same pattern as every other trim through Denali. Only Denali Ultimate includes the diesel standard.

Frequently asked questions

Does AT4 come standard with the diesel engine?

No. AT4 runs the standard 6.6L V8 gas engine with the Duramax 6.6L Turbo-Diesel available as an upgrade, the same as Pro through Denali. Denali Ultimate is the only trim where the diesel is included standard.

What's the real difference between AT4 and AT4X?

AT4X adds a factory-installed 1.5-inch suspension lift with Multimatic DSSV dampers, a rear electronic-locking differential, 35-inch Goodyear Territory MT tires, and a more heavily upgraded interior — genuinely different off-road hardware, not just trim-level badging. AT4X is also priced meaningfully higher, starting at $85,200.

Is AT4 available on both the 2500 HD and 3500 HD?

Yes, AT4 is offered across the Sierra HD lineup on both chassis. AT4X, by contrast, is primarily associated with the 2500 HD in current GMC materials — confirm 3500 HD AT4X availability with GMC Danvers before assuming it's on the build sheet.

See AT4's off-road hardware in person

GMC Danvers can typically arrange a side-by-side look at AT4 against both SLT and AT4X. For the truck that goes further off-pavement, see the AT4X guide; for the full lineup, see the Sierra HD overview.