<_< Have a 91 bronco, eb, 351, E4OD, 4" superlift susp., Had Driveline services rebuild rear shaft inc. cv joint and new sealed spicer joints at both ends. Vibration comes on at about 40 miles per hour and disapears shortly after. Trans shifts so softly (yup, it's irritating) am not sure its happening during shifts, or just before or after. Does anyone ahve any ideas?