I have an 88 Sport Coupe Thunderbird, ever since is got the car the speedometer has been off. 35 is 55, 55 is 75. and so on and so forth, the speedo is the stock 95mph, stock trans, and a 3.73 rear gear. The gear in the tail shaft is a 19 fir the sensor and a 7 if I counted it right. This is very annoying when I let someone drive the car, and they complain about the speedo, and I have to say that it is very aggravating not knowing my speed. I could really use help with this.