[Dick Carne]

I agree that a good initial step would be to remove the plugs, jack up the rear axle, and try to determine at what point in the driveline the motion seems to stop. Several years back, I incurred a similar experience with our roadster - turns out that it was one of the pinion gear nuts had backed off allowing the pinion bearings to be subjected to abnormal back and forth, eventually coming loose and getting caught in the ring gear. I hope that this is not the case, but it sounds very similar. Please let us know what you find.