Actually it was '57, '56 for GMC. The parts were still outsourced from NAPCO, but the assembly was done at GMs plants.
A little 4x4 trivia-GMC was the first manufacturer to offer a v8 engine and automatic tranny in a 4x4. I know the Jeep guys like to claim they did it first in '62, but GMC offered those options in '56, 6 years earlier.
