Inner axle seals

Agreed, Same thing with a bad wheel bearing on a front wheel drive car. I can diagnose which side its on but they both have the same number of miles on them. I always recomend replacing both.
As for those rear axle seals... never expect the gear oil to lube the bearings and seals. You'll burn them up before you get out the driveway. I pack axle bearings and seals with a heavy grease (white lithium sometimes). The gear oil has a hard time getting past my grease barrier in order to leak.