It is my understanding, if you have a wood plank bed, Chevrolet painted it black at the factory. (Do a search on Stovebolt to see the numerous threads concerning paint type.) This was an inexpensive yet extremely effective weatherproofing applied to the boards.
I don't have anything authoritative on the bed walls being black. This painting sounds odd since they probably would have a done a single-color "paint bomb" to get the truck white in the first place. It would have taken effort (read "money") to make the walls a different color. Since this is in such an unobvious location, I could see it being white as well.
I'll sit back and watch to see what the experts post.
Bill
