[FlatheadTed]

Maybe leaking from the lower cluster shaft ,you may need to roll the Differential back and split the rear gearbox mount ,weld up some ears on the mount to cover the shaft ends. Then fit new gaskets or you might be able to clean the oil of and seal it the best you can with silicone with out doing megger work .Any new gaskets need a gap filler sealer as well ,any drip over is there to lube the bearing on the drive shaft .