Hi, saturday i put the Imp on a lift to see how is the center bearing, driveshaft (i've a leak at the "nose" of the rear end: the oil seal is new (3 years) but ther's a small leak. i must put a new one but perhaps put a very thin sleeve behind it to move the lip contact area). The mecanic found that the flange nut wasn't very tighten, he removed easily the nut (this nut must be torqued at 240 ft/lbs) with air ratchet gun. he tights again the nut with his tool and now the shudder has disapeared ! I remember i tight this nut some years ago when i replaced the seal but perhaps with vibrations of driveshaft (i had to replaced the center support which was very worn) the nut became a little loose so the pinion bearings were not well loaded. I hope that i haven't damaged the 2 bearings, i 'll check the front bearing when i'll replace the oil seal (it seems that Napa have them). I think also that when we tight the flange nut we preload the bearings. Does the 240 ftlb torque must be reach ? I don't have new adjusting shims bearings and it seems that the preload of the bearings need special tools -- Philippe COURANT (Pau, France) Imperial 57 Crown convertible Buick 58 Roadmaster sedan - American Car Club de France (ACCF) : http://www.accf.com - Chrysler Imperial France : http://www.ifrance.com/c-i-f - Cadillac " Standard of Excellence " : http://www.ifrance.com/accf-cad - SportsCars : http://www.ifrance.com/accf-sprtcar