With a towing capacity of up to 36,000 pounds when equipped with the 6.6-litre V8 turbo-diesel engine, the GMC Sierra HD enjoys a loyal customer base made up of buyers who value capability above all else. But recently, the segment has welcomed variants equipped with more than just towing technology, including models focused on off-road driving. The AT4X model represents the Sierra HD among these rugged behemoths, and is notably equipped with 38 mm raised suspension with Multimatic DSSV shock absorbers.