I just baught a 49 Plymouth Suburban. Its got a flathead L6 in it stamped P28. If the motor is from a P28 then the generator and ignition components should be 12 volt neg ground. A 49 Plymouth however is 6V pos ground.

Currently I have the motor out of the car. Is there a way to test generator to make double sure its 12V without having it in a running car?