Did some nut and bolting on the car today. Of the 4 diff -> subframe bolts, one was absent and 2 were loose. Knowing how much of a pita it is to get the diff precisely located so the bolts will go in, instead of replacing the missing bolt, I put a stud in.
Red locktite where the stud threads in the diff. Blue locktite for the nut.
The trick way to do diff fasteners is to replace all 4 bolts with studs. The studs are readily available at your local autoparts store as 12mm? wheel studs. For the rearward two, you then drill 2 holes in your trunk for easy access to the nuts. This allows you to press the diff right into place w/o spending an hour fighting to get the bolts started. I only replaced the one stud instead of all 4 tho. I was lazy.