Originally Posted by Mercury

Love the pic of Toby

The drive shaft is something of a tight fit. Did you remove the center mount? I had to remove the parking brake in order to allow the drive shaft to flex enough to make it in or out.

Since this started as a vibration issue, let me make a suggestion. This comes from experience. When you have the driveshaft out, check the u-joint for a notch. Move the joint slowly from side to side to see if it has a notch in the centered position. Test both axes of rotation. If it does have a notch, you will need to replace the entire shaft, as the (bad) u-joint is pressed in. The vibration you were feeling, and a busted mount were exactly what I witnessed on my car. If it is notched return the new bearing and mount, as the new driveshaft will come with them.

You can remove the flex disc without removing the tranny mount. Your choice.