My '09 XF Supercharged (4.2) has developed a whine from the rear which has been diagnosed as a bad bearing. No amount of searching has anyone been able to identify or locate this bearing. Does anyone have a clue or can point me in a direction?

 

If you can't find the bearing, take it to your local bearing supplier & he'll be able to match it for you. Or get your garage to do it as long as they're experienced with diffs.
Time to consider a Quaife LSD instead after comparing costs ?