to be free of terrible harmonics. Tried many clocked positions at diff, still had bad harmonics. The factory put the 2 piece there to reduce the effect of the harmonics. Also replaced the tranny rear mount at the time. I gave up returned the 1 piece and put the 2 piece back after rebuilding the center bearing area, bearing and rubber was shot. I paint indexed the parts before removal. Works perfect on my 92 with the original DS.
Problem with DS balancing is what rpm do you balance it at to take care of the several order harmonics. The DS always rotates at rear wheel rpm x diffy gear ratio and at 60 mph on a tire with 24" diameter that is about 3500 rpm and double that at 120 mph and 1/2 that at 30 mph.
Some here have had some level of success with 1 piece and they settleded for more harmonics than stock 2 piece.
