I'd check that pan gasket first, since the leak seemed to have happened all at once. In my experience, the seals wear more gradually.
In any event, the rear tranny seal isnt too bad to put in, provided you have the right socket. The drive sdhaft must come off. The front seal needs a tranny removal.
'84 190E 2.3
'83 Porsche 944 (track car)
'84 Porsche 944 (parts car)
85.5 Porsche 944 (sled)