Hi, I just bought a '67 GMC C-10 pickup and found that the spedometer driven gear is missing. It's a 3 speed Saginaw transmission with 3.73 gears. Tires are 15".My mechanic told me that the drive gear is still there but he doesn't know the number of teeth on it without disassembling the transmission. Does anyone know what speedometer gears came in this truck. Thanks is advance.Doug