2024 GMC Sierra 2500HD AT4X First Look: Heavy Duty, Professional-Grade Off-Roader

It's the logical question following the 2024 Chevrolet Silverado 2500HD ZR2's announcement: What about GMC? When will there be a GMC variant? Thankfully, yes. As the Chevy HD follows in the footsteps of the half-ton Silverado 1500 ZR2, so too does the GMC HD carry the AT4X moniker from the Sierra 1500 AT4X.

The 2024 GMC Sierra 2500HD AT4X—and especially the range-topping AEV Edition—takes the already utterly desirable, tamer off-road AT4 model to the next level of off-road prowess (should there be such a thing for an HD truck). It's a whole lotta truck, coming straight for its three-quarter-ton heavy-duty off-road competition that include the Ram Power Wagon, Ram 2500 HD Rebel, and Ford Super Duty Tremor.

As expected, the Sierra 2500HD AT4X is mechanically akin to the Silverado 2500HD ZR2, meaning it gets MultiMatic Dynamic Suspension Spool Valve (DSSV) dampers paired with a factory-installed 1.5-inch suspension lift for increased ground clearance. "Specific" upper and lower control arms and steering knuckles round out the suspension mods. A front aluminum skid plate and underbody steel transfer case skid plate protect vitals while off-road. Approach/breakover/departure angles for the AT4X come in at 31.6/25.7/21.2 degrees.

It rides on aggressive 305/70R18 Goodyear Wrangler Territory MT tires—basically 35-inch tires (34.8 to be exact)—mounted on 18-inch aluminum wheels. There's a rear electronic locking differential (but no locking front differential like the smaller Sierra AT4X, as the girthier HD Sierra truck would likely destroy it). A new Off-Road Mode adjusts things like the anti-lock brakes, traction control, transmission shifts, and throttle for extra-gnar off-road performance.

The exclusive Obsidian Rush interior of the 2024 GMC Sierra 2500HD AT4X provides optimal retreat from the elements: power massaging front seats, full-grain leather-wrapped seats throughout, Vanta Ash wood décor, and a 12-speaker Bose Premium Series audio system with Centerpoint surround technology. A 13.4-inch infotainment touchscreen, 12.3-inch driver information center, and 15-inch head-up display characterize the upscale interior.

Configured only as a 2500HD Crew Cab Standard Bed four-wheel drive, the GMC Sierra HD AT4X is powered by the standard 6.6-liter V-8 gasoline engine (401 hp/464 lb-ft of torque) or the venerable 6.6-liter Duramax V-8 turbodiesel (470 hp and 975 lb-ft), both backed by an Allison 10-speed automatic transmission.

The heaviest AT4X, the diesel AEV Edition, weighs 8,605 pounds (woof), and the highest payload is 3,291 pounds (AT4X gas). Maximum traditional towing comes in at 18,500 pounds (AT4X diesel), and fifth-wheel/gooseneck towing is at 18,000 pounds (AT4X gas). Trailering technology and assistance abounds: Transparent Trailer View, Trailer Side Blind Zone Alert, Adaptive Cruise Control with Trailering, and 14 available camera views.

The GMC version of the special-edition Silverado 2500HD ZR2 Bison (co-developed with American Expedition Vehicles, or AEV), is called the AT4X AEV Edition. This alpha AT4X gets stamped steel AEV bumpers with integrated recovery points and front winch capability (c'mon, just give us the winch, too). There are heavy-duty steel skid plates to protect the engine, steering rack, transfer case, and exhaust. Sleek 18-inch AEV Salta wheels, distinct exterior badging, AEV-logo'd front-seat head restraints, and AEV-branded floor liners round out the Sierra HD AT4X AEV Edition. It'll be available in gas and diesel; the added gear adds about 375 pounds to both.

Look for the 2024 GMC Sierra HD AT4X and AT4X AEV Edition to hit dealerships in the fall of 2023, following the Silverado HD ZR2's end-of-summer arrival. Pricing has not been announced, but if we had to guess, the AEV Edition will top the HD Denali Ultimate's $94,000. If we were betting folk, we'd put our money on the Sierra HD AT4X as Overland Expo's next "Ultimate Overland Vehicle. "