When I first got my 53 1/2 ton on the road, I welded two pieces of Angle Iron (from an old bed frame) to the inside of the bedsides. Then I got a 4X8 sheet of Marine Grade Plywood, cut some grooves in the right places for the bed strips with my circular saw. Spar Vanished it, dropped it in the bed with two 3/4 X 3/4 pieces of tubing on either side to take up the extra space, then bolted the strips all down (and to the cross members).
I ran it that way for several years until I took the truck apart for the recent rebuild. I set the bed off the truck in one piece with the wood still bolted in, that bed will likely end up on another truck I plan on building to drive.
Mongo
