Just to add to the list... There was also a very rare aftermarket Torsen rear diff for the 2.6.

The factory rear LSD is a decent part. There was a TSB on it to reduce it's grip to deal with shuddering problems some owners had. If I remember right the fix was replacing / removing a set of clutch plates. It's possible to add extra clutch plates as long as you run the right gear lube (Redline is a favorite). My experience was that most shuddering problems could be cured with the right gear lube and the TSB was not needed.

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...