Report: Off-Roady Yukon AT4 Won’t Come with Diesel Option by Sebastien Bell May 7, 2020 Share Comments Although the 2021 will have access to a Diesel engine, the off-road-ready AT4 trim won’t be available with it. The reason, according to GM Authority, which spoke to unnamed sources, is the AT4’s special front fascia. The lower section is cut off higher than on regular trims to allow for a better approach angle. 2021 GMC Yukon AT4 This unique design, though, would obstruct the intercooler and its piping necessary for the 3.0-liter Duramax Diesel engine. According to GM Authority, that’s the same reason the Tahoe Z71 isn’t offered with the LM2 turbodiesel engine. For the Yukon AT4, that leaves just the 5.3-liter V8 that makes 355 hp and 383 lb-ft of torque—which should probably do. It will be paired to GM’s 10-speed automatic transmission with a two-speed active electronic Autotrac transfer case.