It is possible that the rear axel seals are leaking due to oxidize oil build up under the seal lips cuasing a poor mating surface between the seal lip and the axle surface. It is possible that cleaning with Auto-Rx could solve the issue. It also may be due to sheared down gear oil that is much less viscous than what it should be. It would be worth a shot adding 2 fluid ounces per quart of gear lube in the rear end and running it for 1000 miles to see if cleaning can solve the issue. Even if it does not solve the issue, you would want to dissolve any varnishing and so forth before draining the gear lube and putting in fresh. You will drain out more contaminants out of the whole banjo by running some Auto-Rx in it before draining. With respect to the tail stock on the transmission, this may be the same issue. Spent transmission fluid can build up contamination on and around the polymer seal boot creating a less than desirable mating surface.
Either case, the repair cost of replacing these seals are not that expensive. You may want to check the universal joints on the drive shaft for wear or excessive play. This may be causing the drive shaft to spin out of round, or out of balance.
