You could try to take an old seal and the stub it rides on to a bearing shop. they may have a triple lip seal available, and/or a sleeve to put ove the worn spot that you probably have on the stub.
You need the old seal to get a good measurement on the OD of the seal, a measurement of the ID of the hole it goes in would be better, but you don't want to take the tranny in with you! :wink: The stub will let them measure for the ID of the seal.
Good luck!
Anyone know if he can chage the offending bearing (bushing?) without pulling everything apart?