Not quite....
I have talked to the GM Heritage Center and I purchased the original invoice. I am guessing you could order whatever color you wanted to back then as long as you paid a couple hundred bucks. This one was ordered by Camp Customs & Vans I. Riverside, CA.
I think I have a rare bird in regard to the factory color on my 1991 C1500. Color code is WE5822 on the Glovebox, which was only available in 1972 (According to my Googling). Any idea how this truck could've been painted that color at the time?