Originally Posted by Equinox

I would def suggest dropping the diff, or at least taking off the rear cover. I DO NOT SUGGEST drill and tapping a hole with the cover in place. Even when placing the temp sensor low (which is what I did, to measure the reservoir) there are a few baffles inside that can block the probe from mounting properly. You should drill and tap once you are able to view BOTH sides of the cover.

On my picture, you will see I have the temp probe (brass, at the lower right corner of cover) and the drain plug is now an AN stainless fitting, as well as the fill hole. My setup uses the temperature probe to tell the pump when to turn on and off, only circulating the oil once it reaches a "high" temperature, and not while just at normal operating temp.