I'm sure someone out there can supply you with that... I have replaced those areas on cars before vs replacing whole brace and skin. Put a wanted ad up and I'm sure you'll find something. I have a front piece, but no rears.
68 Road Runner, 69 Belvedere, 71 Challenger Vert
340 barracuda, 01 Ram CTD, 95 Ram, 04 Ram, 85 Daytona turbo Z
99 Trans Am, 66 GTO, 06 Magnum RT AWD