The truck has already been converted to 12v. I know you can apply 12v to a 6v starter, but that isn't a very good permanent arrangement. I see now that just adding a solenoid isn't the answer per klhansen above. I have only run the truck to move it around the yard, and the previous owner the same, so I don't know if the starter and flywheel have been correctly changed.- What are the different tooth counts for the 6 vs 12v flywheels? I can put it on the lift, and remove the inspection plate and start counting teeth.