My 68 122 (with auto trans) is makkng a momentary thump, thump thump sensation when accelerating after a complete stop. The drive shaft support retainer was replaced, but NOT the driveshaft bearing. The drive shaft was reinstalled but the vibration is still occuring. It only lasts for approx 2 to 3 seconds.

Unfortunately, while removing drive shaft we failed to take note of the U joint alingment while separating the shaft spline.

Any recommendations, resolutions, comments would be greatly appreciated. Thank You