the cork gasket at the end is piss ease to change, the other place they leak from is the driveshaft seals but not as comon, the only other gasket is for the 5th gear casing to the main gearbox,,,,, but thats a pro job to do as you need to take off 5th gear and also getting it back together you have to line up the selection forks or it wont work

most comon leak though is from the end cap with a 3 quid gasket thats made of cork