Hy Dodgebum, your starter is a six volt one, application 1938 to 54 GMC and Chevrolet pickup. The armature on six volt starters is larger in diameter than twelve volt starters, so you will need a starter drive for a six volt starter. Another point, you said you now have a 1957 engine, do you know which flywheel was used on that engine? Six volt flywheels have 139 teeth twelve volt flywheels have more, the number escapes my memory at the moment. In short six volt starter drives are compatible with six volt flywheels and twelve volt starters are compatible with twelve volt flywheels. Before you attempt any repairs count your number of flywheel teeth and report back here.
