Inner seal for green bearings

National 8695S

There's a cheap one at O'rielly's for 1.49 ea...

http://www.oreillyauto.com/site/c/search.oap?keyword=8695s

At least you have some numbers to cross reference. the ID of the seal is 1.55"

how can you tell that this is the correct one?
i'm not doubting you at all..but i just have no idea what the part is actually supposed to look like, and i want to make sure that i buy a seal that will actually keep my gear oil sealed in there..thanks for taking your time finding that crackedback!