Here you have the Input Bearing Spud. You can see the Huge Drive Splines that Lock the Synchro Hub to the Main Shaft. Remember these are the Primary Force Transmission Splines. Your Synchro Hub should be Press fit. Good and tight. Not slide on and off. If that is the case one of them is garbage. They have to be Baby's Ass Smooth. The Gear rides on these lugs
