The rear main seal often develops leaks as time wears on - and our cars are only getting older. While you do have to drop the oil pan to replace the rear main seal assembly, if you are putting in a new clutch, thats the time to as the transmission is already out.
Seal Assembly w Case - 91-92 TT/VR4 & 91-99 Non-Turbo
Seal Assembly w Case - 93-99 TT/VR4