Those parts have compound curves: how ya gonna make that with a sheet metal brake?
My current bed has a quarter panel replacement/repair panel installed that somebody must have repaired before I got it. I think they stopped carrying them after these vehicles became 10 years old. In any case the few body shop supply houses I've contacted don't carry them now.
A shop in PA called
B&G Fiberglass builds what looks like nice fiberglass beds if you want to go that route. . There's also,
toyotafiberglass.com up in BC Canada. They make f/g o/e style bed sides. -- Matt