Need help troubleshooting this dilemma.
Car: "Crappy Gas Pipe" 1984 300D turbo GreaseCar. 230k
Symptoms: Originally had a loud rumble under car while coasting on highway.
After stopping and starting up again there was a vibration in the shifter (Floor Automatic) Grinding noise louder now. Shifter is shaking while in gear. drove 1/2 mile @ 1 mile per hour to get to somewhere I could ditch the car.

Things it cant be: Flex discs and center bearing replaced a year ago. Front brakes and wheel bearings are new. Motor mounts. Down pipe for exhaust.

Three Tranny shocks?: Only two, one on each side, the back/center one is missing. Must have been for years.