I drove 6 volt GMC's daily well into the 60's and 2 of them into the 70's. I never had a compelling reason to change one over. Too small cables gives 6 volt a bad reputation. So does a dragging starter, but 12 volts won't fix that. 6 volts never seem to go totally dead like 12 volts. Seems like you can always get one more start out of them. My jalopies that were born with 6 volt are staying 6 volt.
