this was one problem i did have. No matter how much i shimmed or tighted the bevel and joint cup together the teeth of the bevel would dig in the diff cup. Actually that's not true. I did not have it shimmed right, then finally got the right shimming but the plastic pieces were still stuck in the conical gear. So i had to dremmel off that part of the diff cup. And at first i had the problem of the conical hitting the housing too.
The best answer??? Sand the shit out of all diff cups and housing's before assembly. THis will save you mucho headaches
oh this only happened on my front diff BTW.