I installed a 4.10 gear and i had to get a speedometer gear for the transmission to get the spedometer right. My spedometer was off by about 15mph. I as told to get a 23 tooth speedometer gear. I bought a 23 tooth speometer gear, and the spedometer is still off. Not sure how bad off now, but it is still off. If anybody knows anything about this, please let me know. Thanx