worn driveshaft
 

anyone had a worn driveshaft that would make a thumping noise

The flange that bolts to the tcase on mine was so worn out you could rotate the ujoint caps with the end of your thumb and they would bang back and forth against the snap rings. I don't know if that's the same sound or the same problem but you don't want a shaft to fail at highway speeds. Just get under your truck and yank and twist while looking for movement.