Drivetrain Vibration

DRIVE SHAFT!! Have another shaft built at a different shop. Had a customer years back with the same issue. We put my driveshaft in his car to try and the vibration was gone. After measuring his we also found it was to long. It was good while in the air but bottomed in the trans while on the ground. What car do you have and what is the length of your shaft center of cap to center of cap. There is a shaft length chart for different bodies in the DC manual. Balancing the shaft doesn't mean its clocked or the ends trued they could be installed at a angle.