1973 Mercury Marquis mileage: 150,000. My son and I rebuilt the C6 transmission. Now we have reverse and no forward at all. We checked the governor and replaced the vacuum shift module. In addition, we made sure the linkage was shifting the valve. We even pulled the transmission and took it apart and put it back together again to made sure that we had not put something together wrong. Everything is exactly as the manual said it should be. Thank you for your help.