I have been a member on here for many years and have read about noise issues from the cars rear. Many have been wheel bearing related ( as you surmised). I don't remember that many being rear diff ( if any). Other causes have been poor quality tyres; ( road noise) prop shaft centre bearing, to name alternatives. I changed front off side drop link cos thats where I heard noise from...Turned out it was nearside that was chattering- old age deceived me
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Cheers Bob.