Does anyone know if there is a aftermarket company that manufactures fiberglass replacement bed sides/panels (outer)? I have had my '96 f150 to the body shop on a couple of occasions, and the rust keeps coming back (above rear wheels).

 

Get rid of the rust and put a Generic roll on bed liner on the wheel wells. If your set on fiberglass check out Autofab.com

 

take it to a better body shop they're not doing what they need to do to get rid of the rust they're just covering it up