I have not worried about any rear diff issues in nearly 10 year.

Ya know why? Because I bought two S60-s after reading and seeing all the "like" junk posted here and having a stock 440-6 auto car shred a 8 3/4

Now in these times, used 8 3/4 prices have gotten really stupid to the point some are within a few hundred bucks of a basic S60.

Overbuild a dam and you will never get your feet wet.

Sorry but my opinion is spending money on a 8 3/4 these days is like tossing money in the trash with a healthy stroker build and some serious driving.