GMC Sierra HD AT4X
The GMC Sierra HD AT4X is an upcoming trim level of the GMC’s full-size, heavy duty pickup truck that will join the Sierra lineup for the 2024 model year. It will be offered alongside the “regular” GMC Sierra HD AT4, while delivering higher levels of capability, equipment and features.
|Model Year Availability||2024 – present (expected)|
In March 2022, GM Authority exclusively reported that GM would be adding the Sierra HD AT4X to its lineup as part of the upcoming refresh of the Sierra HD, then expected for the 2023 model year but subsequently delayed to the 2024 model year as a result of delays brought about by the COVID-19 pandemic. Shortly thereafter, we spied a mysterious Heavy Duty GM pickup undergoing testing that seemed to line up with our expectation of the Sierra HD AT4X.
In August 2022, we once again spotted a prototype undergoing testing, confirming that the Sierra HD AT4X is currently in development. Notably, these spy shots seem to indicate that the upcoming GMC Sierra HD AT4X will not feature Multimatic DSSV dampers, which are included on the Sierra 1500 AT4X.
The suspension in the Sierra HD AT4X is expected to be more capable in general than the “regular” Sierra HD AT4, but it likely will not have DSSV dampers. Further expected upgrades include front and rear e-lockers, beefy Goodyear Territory MT tires and raised ride height.
Additionally, the 2024 GMC Sierra HD is expected to receive a midcycle refresh that consists of new front and rear ends along with an all-new interior, which we recently spied for the very first time. In addition, the 2024 GMC Sierra HD refresh is expected to introduce an updated version of the 6.6L V8 L5P turbodiesel Duramax engine, as GM Authority was the first to report. Rumor has it that the Duramax may be upgraded to produce roughly 1,100 pound-feet of torque and more than 500 horsepower, providing plenty of power to this range-topping pickup.
Meanwhile, the naturally aspirated 6.6L V8 L8T gasoline engine will likely be mated to GM’s ten-speed automatic transmission, replacing the six-speed auto used in the 2020, 2021, 2022 and 2023 model years.
We expect the GMC Sierra AT4X HD to become available in mid-2023 as a 2024 model year vehicle.
Discuss the GMC Sierra HD AT4X in our GMC forum.
Sierra AT4X HD News
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Another look at Big Red’s upcoming heavy duty beast.