I have a '68 LeMans that has had a 428 (375 hp) and we believe a Grand Prix posi installed (either '68 or '69).
Recently a rubbing/grinding noise came from the right rear wheel. Upon removing both rear drums we noticed they are different (and have been for at least 10 years)! The subject drum is larger (possibly from a 68 full size or front drum). It is being scored on the face of the drum (towards the lug holes) presumably by the sides of the shoes. The axle can be moved in or out about 1/8" which I hear is normal. The drivers' side doesn't move at all. What is causing this?