The rear axel is a Kung Ten W5ER from a 1999 Trek 4000. The freehub was sticking so I was taking the axle apart to free up / clean / lube the freehub.
I noticed after it was apart that there are 2 sizes of ball bearings for the axle, and I don't know which side gets the bigger bearings.
I know I'm in trouble, any ideas out there?