""The LHS seal usually leak because the diff bearings on that side wear, due to the gearbox oil not being changed regularly, and particles getting into the roller bearings. To check, see if you can move the drive shaft laterally, (up and down) adjacent the seal. If you can, no seal replacement will fix the oil leak. The bearings are under preload, and there should be no side movement. If there is movement, it's a strip down of the gearbox and diff.""
Possibly my problem ?