I think I may have found my answer in the pic in post 1, assuming this truck is original paint:
http://67-72chevytrucks.com/vboard/s...d.php?t=689629
This makes sense. I like fawn interiors, but not with blue vinyl! So, of course the trim RPO brought with it the interior paint color. Kinda cool to have solid ivory truck with the interior painted blue. Hmm.