All, regarding the gear diffs and the expected "warping" of the mold.

Make sure when you are building it that the flash from the moulding on the smaller housing near the screw holes is flush, best to clean it with an exacto.
I have seen a couple of diffs that have been built with this issue so far and fixed them by just making sure there is no left over flash from the mold.

I would say a 99.9% guarantee.