Ten years ago, I got an excellent 1/2 ton 1954-bed mat from a reproduction parts vendor (LMC or Brothers, I think). I cannot now find it listed.
It was thick wide-ribbed rubber and had many small "nubs" on the bottom (to assist in drying underneath). Be careful with moisture being trapped underneath (and/or being held in an absorbent cover, such as a plywood cover).
Maybe someone can comment on the 47-55 bed dimensions matching the Chevy step-side short-bed dimensions through at least 1972.
The nice thing is that the dimensions are a clean rectangle. Several vendors sell bed-matting material that can be cut.
