Thanks TnBob, the differential oil level checked about 1/4 inch down but the car was jacked from the right rear making the car lean to the left and down in the front which I think would account for the 1/4 inch. The rear flex disk looks good, no cracks and bolts are tight.
I am running Lucas 85-140 gear oil, just changed about 7000 miles ago. I change it every 30k and have been doing it for the last 12 years.

Thanks for the reply. Anything else you can think of?

PaulM

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84 500 SEL (307,xxx miles)