HD11E- rear main seal leak

Hello room, I have been given a project on my friend's Allis Chalmers HD11 dozer. we parked it 20 years ago believing the rear main seal was leaking on to the clutch. I have called a parts house and they advised me it is not a rope seal but a rubber seal and a wear sleeve. My question is, generally speaking, how would I replace this seal? the transmission/flywheel needs to be removed to expose end of crankshaft?



any help would be greatly appreciated..