After rolling out the off-road-ready half-ton Sierra All Terrain X earlier this year, GMC is doubling down on the theme with the just-introduced Sierra HD All Terrain X.
The Sierra HD All Terrain X begins life as a 2017 Sierra 2500HD SLT crew cab with four-wheel drive and the All Terrain HD  package. As such, the All Terrain X includes features such as a spray-in bedliner, front and rear park assist, a heated steering wheel, leather seats, and the Off-Road Suspension package, which brings twin-tube Rancho shock absorbers, hill descent control, and an underbody skid plate.
Separating the All Terrain X from any run-of-the-mill Sierra 2500HD with the All Terrain HD package, though, are a host of model-specific items such as 18-inch black-painted wheels wrapped in chunky Goodyear DuraTrac on-/off-road tires, a bed-mounted sport bar, black side steps, and a body-color grille surround and door handles. Available in one of two colors?black or white?all Sierra HD All Terrain X trucks also wear black bumper trim as well as black mirror caps and beltline moldings.
Buyers can opt to have their All Terrain X powered by either GMC’s 6.0-liter V-8 engine with 360 horsepower and 380 lb-ft of torque, or the brand’s new 6.6-liter Duramax turbo-diesel V-8 with 445 horsepower and 910 lb-ft of torque?an engine we recently experienced in our brief drive of the 2017 Chevrolet Silverado HD.

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