hello matey guess your referring to the nose end (bit the prop bolts to?) could be that it,s time to re,torque the nose bearing the diff has a crush tube that applys the correct meshing of the gears. after a period of time wear sets in and allows very slight movement on the output shaft which is then transfered to the seal allowing it to leak try applying the hand brake and foot brake applied then disconnect the prop with a large torque wrench/ tommy bar turn the flange nut 45 degrees and check for play that 9 time out of ten cures the leak failing that you,ll have to replace the seal and crush tube hope this helps
