GM Authority has learned from sources familiar with the matter that General Motors product planners are considering development of a new GMC Sierra HD AT4X model to slot in above the “regular” GMC Sierra HD AT4. The new GMC Sierra HD AT4X would join the “regular” GMC Sierra HD AT4 in the heavy-duty pickup truck lineup, rather than replace it.
The 2023 model year will usher in a refresh for GM’s heavy-duty trucks, including both the GMC Sierra HD and Chevy Silverado HD. Per GM Authority coverage, early 2023 GMC Sierra HD prototype models are already out and about testing in public, with updates expected to include new exterior styling for the front and rear fascias, as well as an all-new and much-improved cabin space.
What’s more, the refresh will introduce powertrain updates for both the naturally aspirated 6.6L V8 L8T gasoline engine and 6.6L V8 L5P turbodiesel Duramax, as GM Authority was the first to report. Rumor has it the Duramax may be upgraded to produce a whopping 1,100 pound-feet of torque and more than 500 horsepower.
If General Motors does end up green-lighting the new GMC Sierra HD AT4X, it will feature a broad variety of off-road-ready equipment, starting with new high-clearance bumpers front and rear for improved approach angles and clearance. The greasy bits will be protected with durable skid plates that supersede those equipped by the “regular” GMC Sierra HD AT4, while the suspension will be more capable as well. To note, the current AT4 HD features twin-tube Rancho shocks.
Further upgrades will include front and rear e-lockers, as compared to the lone G80 rear e-locker of the “regular” AT4 HD, as well as even more rugged Goodyear Wrangler Territory MT tires – the same compound featured on the 2022 Chevy Silverado 1500 ZR2. The tires will wrap unique wheels as well.
Put it all together, and the end result should be a rather unique offering. At present, the “regular” Sierra AT4 HD rivals the Ford F-250 Tremor, while this new AT4X model would expand the lineup and take things a step further. To that end, GM is already testing a next-level version of the light-duty GMC Sierra AT4X 1500, as GM Authority covered previously.