The next-generation Sierra HD exterior is more visually distinguished from the light-duty Sierra with the redesign. In fact, the Sierra HD shares only its roof with the light-duty. All other visible elements are unique to the work-focused HD truck. The standard engine is a 401-hp, 6.6-liter direct-injection V8 with a six-speed transmission. The other choice is a 445-hp, 6.6-liter turbodiesel V8 engine with an Allison 10-speed transmission. The current model is quite a bit bigger than the previous model in all dimensions, riding on a 5.2-inch longer wheelbase, measuring an extra 10.4 inches bumper to bumper. The maximum towing capacity for the diesel crew cab version is 31,400 pounds, and the maximum payload is 5,890 pounds. Available advanced safety systems include FCW, AEB, BSW, and rear cross traffic warning.