I bought a 83 sedan in june. I've had a vibration that seems like its coming from the mid to rear on the car. Its starts at about 45 to 65. At around 70 it seems to smooth out. It feels like it oscillating. At the higher end (65) the shifter vibrates at a very high frequency. I've had the transmission rebuilt and one of the axles replaced for torn boots. The universal joint replaced. flex disks look good. Was thinking maybe rear end. At the end of my rope. Any ideas out there?