What is a good source for replacement panels for a 1980 F-150 8 foot box, both left and right side. Also, canI just get section panels for the box floor so I can just replace a few pieces here and there. Also looking for doors and fenders for the same truck.

 

You might try BroncoGraveyard.com. They have body panels and all kinds of other stuff. Actually, this looks like the page you want. There are a few others out there too like LMC and National Parts Depot.

 

When it comes to reproduction panels, almost everybody (including you local autoparts counter) has access to the same stuff.

But, anyway, here's Auto Body Specialties page for '80-'86 Fords:
http://www.autobodyspecialt.com/cat-sp-10/175.gif