Axle seal

1988 Bronco 2,2.9 engine,4WD. Does anybody else have a problem with the left rear axle seal? Axle is good,no wear marks,replaced wheel bearing,tried a repair bearing(offset seal),leaked after a week,replaced axle with salvage yard axle,have used 3 name brand seals,no obvious cracks in housing,diff. vent is clean. Any ideas?

axle worn outside spec, and wearing the seals too much.

Replace the wheel bearning if it is still a problem you may have a bad diff. Is it making a loud noise when you put it in reverse?