Oh er, Roger I think you are getting me confused with some on technically minded.
I fitted a shiny new / refurbished diff. yesterday, drive shafts and exhaust back on today brakes and wheels tomorrow.
The back end is still up in the air and if you give me some idea what I can do to give you the answers you need (if I am not too far advanced) I'd be very happy to do it.
My initial assessment some weeks ago was limited to jacking up the car and rotating the wheels until I felt the resistance of the diff. result was about 2" in old money at the top of the tread before anything happened.
With the old diff off I noticed some play and a grinding noise from the near side inner shaft, I had thought I could hear something from that wheel while I was driving about, Confirmed with the diff off and up on the bench. I also found One of the UJ circlip type things flush with the yolk just rusted and gunged in place so that is reseated and the clip thing back in the groove.
Have discovered that the three "spare" driveshafts must have been an earlier type as the have the fine threaded screw on joints between the two outer shaft bits.
so the old shafts have been cleaned up regreased and put back into service, will see tomorrow if it was a duff diff............or something else