I had a similar issue and was convinced that it was tail housing gasket. It was driving me nuts with the small trail of
oil running to the back of the car when driving. It turned out to be the o-ring seals at the shifter arms that were leaking, then running down along the tailshaft assy. No easy way to change those without pulling the trans, which I did. No further issues. Not saying that this is your problem, but something to check out.
