tyler,
Typically there is a small, stamped steel washer in back of the bearing that is called a 'slinger'. As the input shaft spins, the slinger "slings" gear lube off and doesn't allow it to migrate through the front bearing and onto your garage floor.
If anything does make it out, that small hole in the bottom of the retainer allows it to drip out before it can foul the pressure plate. The paper gasket seals the bearing retainer where it screws to the tranny case but other than that, it all up to the slinger.
Sometimes, if you park your rig nose down on a steep incline it can leak gear lube. Over filling can get you in trouble too.
While I'm not 100% on this, I believe the later model transmission actually did have a mechanical seal on the input shaft. A sniff test will usually tell you the difference between leaking motor oil and leaking gear lube.
Stuart
