You could try Ply-Do out of Delbarton WVA, they sell parts for old Mopars. #304-475-3245. Don't think their website is fully functional yet but it is at www.plydo.com

Outside of boneyards and Ply-do there are not many Mopar part places. You might want to try Hemmings for parts. There used to be a company that made and sold fenders for old Mopars but I believe most were for the 30's cars. Not sure if they are still around.