I bought the speedo gear set for a 3.73 gear (this is for the T-5 tranny), well I see for the 7-tooth drive gear you have to remove the back part of the trans to put it on? (my trans is out of the car, along with the motor) but don't know if I want to mess with it, if I don't have to.... Is the stock drive gear already 7-tooth anyway? And if so, then I just have to pop out the stock speedo gear and install the 21-tooth one????