I have a 99 ford F-350 with a dana 80 rear differential. It started gradually getting noisy so I took it apart to find the inner pinion and race are shot. I removed them and pressed a new bearing on and drove in a new race. While in there I went ahead and replaced the outer pinion bearing and race.This is where the problem occurs. I put a new seal in and before I even get the nut snug the yoke is rubbing the seal. I take it all back apart to check the bearings and races to make sure they are the correct ones and correct thickness, and they are. I also checked the seal and found it was also identical to the old one. When I originally took it apart it had two shims on the inner pinion and one on the outer between the yoke and outer bearing. I eventially got a bunch of ford nine inch shims and had to shim the yoke about 3/8 inch so it wouldnt rub the seal. The downfall is now the pinion nut is flush with the threads and i am afraid it may back off. It lasted about three days and now the pinion is leaking. I drove the races flush in the housing does anyone know if this is the wrong thing to do? That is the only thing I can see that may cause it to need shimming. Open for suggestions?