I have a 64 f100 with a Berg Warner 4 speed transmisson, 3.89 rear axle and 235/75/R15 tires. The person I bought it from has a 17R 3 speed gear on the end. Does anyone know which gear I should have on it? Does the clip..clip on the same way? When I drive it around my speed is roughly 10 mph slower than what's posted.