I used 1/8" steel stock, sides bent 45-degrees on top for standard flair and welded to 1-1/2" steel pipe ground and bondo'd for roll over, capped at ends. Front, same steel, with pipe roll over. Welded the original stake pockets on. Drilled for cargo hooks on sides. Tailgate drops down on late model strap-style hinges and fastens with sliding door flip-locks into round latches at rear of sides. By-bye chains. Floor is 1/4" diamond plate, POR-15'd on the bottom, primed and painted topside. Will probably coat inside of box with Vortex, Herculiner type plastic coating.
It adds about 200 lbs over the rear wheels, where you want it. Not pretty to everybody, but you can work pretty hard with it.
