69 Tempest 8.2" Diff. problems

Hey, I have a 8.2" B.O.P. rear diff that has a axle wear issue. In 2 years time I went through a set of axles that were new. The proper bearing and hardware was installed. It wore the axle where the inner race of the bearing rides. Is this a common problem or could the housing be tweaked from a wreck or careless driver. Would a Chevrolet 8.5" rear diff from around the same year bolt up without modifying the car or driveshaft. Any replies are appreciated.