Tim,
The link of the photo of one with the wood box is the closest, if not the same thing I'm talking about.
http://www.sheridanzone.com/images/46chevy/stoveboltposts/woodbox.jpeg I've been known to make mistakes, but I felt certain that there was previously a post here on the bolt that described these as a limited production stock bed for the 1/2 ton that was neither, a flatbed or steel sided standard pick up bed.