Vibration issues

You replaced the tail bushing and the vibration decreased. I'm sure you didn't re-install the driveshaft exactly the same way. Did you check both u-joints BOTH WAYS? You turn the yoke so the u-joint turns in the caps and see if it moves back and forth smoothly. You have to make sure the rear u-joint is sitting in clean saddles. Including the inner edge that holds the caps from spreading apart from each other. The problem I'm looking for is caps that are too close together; causing a bind and a vibration.