There might be something different with the rear dowel pin fitting into the seal housing. Double check the fit and alignment and also try tapping on the end of the prop shaft while tightening the screws. Doing this will help to seat the front bearing. The retaining snap ring should have a slight taper on one side and you should also see the groove for it has a matching taper. It only goes on one way.
Doing a dry fit before applying any sealer is always a good idea so you can fix any issues first.
