This is accomplished by having the tailgate power down and under the vehicle, with the rear window and back portion of the roof sliding forward. If you're thinking Buick semi-pickup, you're not far off.
But it is a Buick, so there are "club chairs" with power footrests and voice-activated controls in place of the switches and displays you normally find on a dash.
GMC showed off the Terradyne, which is a word combining the Latin for "land" and the Greek for "strength and power" and a vehicle that is one of the division's first efforts to explain what an "authentic, professional grade truck" really is. It has "billet cut" styling with "clean, beveled forms with precise lines around strong, solid volumes."
So it's a hard-butt truck with the kind of lines you saw on the breast-plate of a hard-butt Roman Centurion. The division calls it an "icon for future GMC philosophy and design direction." In other words, "Ave Terradyne, emptori est, te salutem, which is a very bad Latin translation of "Hail, Terradyne, we who are about to shop salute you."
Beyond the appearance of Terradyne lies a flotilla of features that considerably expands the notion of pickup pragmatism -- four "gliding" doors, a cargo bed that expands from 1.98 to 2.43 metres, a mobile office, reconfigurable rear seats, storage bins, a console-mounted laptop, storage in the side panels, and more.