Although the Sierra HD shares its mechanical bits with Chevrolet's Silverado HD, they are no longer visual clones. A higher grille between the stacked headlights lead to a flatter, more traditionally styled hood than the Silverado, and the GMC gets unique fenders, lamps and box sides as well. For this new generation the Chevy Silverado and GMC Sierra do not share near-identical appearance. A new panel forming process gives the dually models integral, seamless fender flares and smoother finish for improved paint.

The wallpaper sized, ruby red GMC logo makes its origin plainly obvious but the bumper that blends into the fenders gives a much cleaner look and is unusual in HD pickups. Increased frame stiffness allows a smaller gap between the cab and body, and combined with the more aerodynamic windshield and narrower door gaps, makes the Sierra much quieter than its predecessor.

The box sides are deeper by an inch-and-a-bit, the tailgate has a optional lock and assist for closing it with less effort, and the cargo management option fits rails to three sides of the bed; these can be used for tie-down points and to carry a variety of tool or utility boxes. The stoutest Sierra HD's can tow 13,000 pounds with the new 2.5-inch receiver hitch, and the new dual-element mirror and trailer brake control options will lower the stress level.

Most HD pickups have external dimensions close to each other and the Sierra is similar; more than six-and-a-half feet wide outside and room for a 4x8-foot sheet of building material to ride flat in the long bed. In 4WD versions the Sierra is slightly lower than competing pickups, and that inch or two could make the difference in commercial garages or fifth-wheel/bed clearance.