1998 Jaguar XJ8 Question: Can anybody identify a rear end grinding noise on a 1998 XJ8.

An intermittent grinding noise comes from the rear end. This only happens during a light acceleration - just above maintaining a speed, and only happens between 35 and 45 m.p.h., so it seems to be a harmonic. The effect has been around for over a year, and has not deteriorated (or improved). I have checked the U.J.'s and bearings, they seem to be OK.