I just acquired this '74 SST and the only rust (and it's pretty bad) is in that little panel below the rear glass and above the trunk lid. Right where the rear glass chrome would attach is rotted. The other 3 sides of that piece where it attaches to the quarters on each side and along the top of the trunk opening are perfect. any ideas on the best, if any, way to repair or replace? Is that a repro part anywhere?