There are two bushings from the factory. The front most bushing supports the U joint yoke and the rear bushing supports the driveshaft. There is a step that the rear bushing and seal are up against. The Oakie bushing I used and the spares that I have have a subtle increase in diameter in the front portion. I guess the idea is for the unit to center before the interference fit is encountered. Mine took a lot of force to drive in.