Other than 4 headlights vs 2, keeping the MY '68 fender shape thru to '72, obvious grille differences, and badging, they are pretty much the same underneath.
In the 67-72 era, these trucks were all built on the same line, with every 6th or 8th unit becoming a GMC.
GMC trucks were sold at Buick, Olds, Pontiac and Cadillac dealerships, and usually had a higher price on the window sticker.
This gave rise to the joke, that the initials stood for ''Government Model Chevrolet.'' Right after the public expose that the US Gov't was paying $570 for a Mil-Spec toilet seat, when the same piece from the hardware store cost $5.70. Rumors that GMC assemblers were screened to have high school diplomas, while Chevy assemblers were hired if they could both draw breath and an X on their contract form, were patently untrue. It was the same people, on the same production lines, illiterate or not.
GMC had been making their own engines, and also used Pontiac motors, until this vintage series. The GMC big V6s were phased out, and Chevy engines installed.
Internal components are identical. Badging and trim details differ. GMC had some exterior colors the Chevy line did not.
Some GMC body parts -- tailgate, grilles, badges -- may be more expensive because they are more rare than the same Chevy parts.
I have one of each and love them both.
