I haven't seen anyone offereing new, assembled and shimmed, ready to run diffs. Even if you go with stronger 1/8th diffs, they still need to be shimmed to fit. I thinks its even more critical with 1/8ths than stock to get shimmed properly.

If you can find a good set of used UE 6 or 8 spyder diffs, those would be rtr and prob outlast your Emaxx.