Need some help with the old girl. (not my wife, the car!) Prior owner installed a shift kit and I believe a different rear end and I hate it. It may be cool on the strip but shifts way too hard for the street. Holds on to 1st and 2nd way too long, speedo is off by about 10/12 mph and now I'm getting an overdrive slip / pulsation. I would love to perhaps put it back to the original. I could live with the a little shift overlap over the whiplash I'm currently getting. Any advice?