Ok I replace the driver side and passenger side rear axle seal because they were blown had no problems with the driver side, but now with the passenger side I cant get the axle shaft to slide all the way in. What could possibly be holding it up? It feels like it goes all the way in but the outer flange will not go all the way up to bolt it in. Don't know what the hold up could be.

 

What year/model truck are you working on?