Thanks for trying to help guys. These are the diffs:
http://www.rc-monster.com/proddetail...HPI_BUGGY_DIFF
One set fits perfect. The other I cannot close the case. I will check again(after work) to make sure it is clean maybe I missed something.
Since this case is the only one that all 4 bearings sit very tight in, it is logical to assume that the problem is the bearing seat in this case. Do you think Mike or FLM could change it out or machine out another .5mm?