I'm not sure about the Willys cars but all Kaiser-Frazer products were 6 volt positive ground. Many people nowadays are not aware of this and connect the battery backwards so make sure yours is connected properly. If it's connected the other way (negative ground), it will appear to work fine but eventually the generator and regulator will burn up. Hopefully someone who knows for sure can come on here and clarify if the 6 volt Willys cars were positive ground.