at about 120k, i noticed that when i would coast, i would hear a dull clicking from the rear -- it would go away under load -- i checked the universal, rear axle cv joints, seemed ok -- so i replaced the differential -- no change -- was fine for 50k more miles, same symptoms -- finally, its gotten worse, had to abort a trip last week, as this noise got louder, only way i got home was to stop periodically and back up -- of course, back in town, at 30mph, it would no longer make the noise -- just crawled out from under, no immediately obvious issues, so now i will start to take the rear end components off -- funny thing is, i seem to remember my old 76 240d making the same noise.

????