Not too long ago I had to replace the center bearing on my drive shaft. Upon putting the shaft with the new bearing back on I lined up what looked like two marks a prior owner had put on the two parts that bolt together at the differential. However, apparently those marks were incorrect and I have a vibration on what was a very smooth car. There are no other marks. I am assuming I will have to again take the shaft off and turn it to the other side and keep doing this until I get a smooth ride. Any other ideas. My mistake was not marking the shaft myself when I dismantled it. Any help would be appreciated.