Stock revo diffs with integy cups? hmm...
I think your problem is they need some very careful shimming to remove the play that is allowing the ring gear to ride past the pinion, which is creating the stripping noise- the ring gear may not be seated properly either.
If you are going BL with this, you might as well ditch them completely and get a set of the hybrid revo diffs in the rc-monster store- they will last forever pretty much with no strippage or alignment issues (if they worked fine before, then chances are your servicing efforts have left them a bit ski-wiff as we Brits like to say
)...