[QUOTE=The Master Cylinder;1949919]And why is that? Where does the grease go?
[/QUOTE
1 because it was never filled or under filled in the first place and 2 because it leaked/forced out. The u-joint housing is not completely sealed and grease can get forced out by spinning u-joint. I have worked on a number of A's that might have had a pump or two in the housing and that was about it. Could get washed out when 600W gets forced thru the rear bearing (not every transmission has newer sealed bearings installed) or bad seal on driveshaft allows it to move down the shaft.
I saw the smile faces after I posted this! LOL