There is a hole in the "tray" under the seat and holes in the lower rear cab corners.
The cab that breathes. I cannot find the illustration, but GM had a picture showing air-flow movement throughout (in/out) the cab. I think that Brad has a good illustration in his slide-show library.
Jim Carter used to sell a cardboard panel the attached a a pick-up seat back cover. The search feature on JCs website is useless - he might still sell that cover. I do not know if it was used on all years or just used until the width of the pickup seat changed in 1950.
