In Reply to: Re: Jumping a battery posted by TheOldHokie on November 09, 2018 at 10:07:12:
Most cars by the 60's had gone to 12V neg ground with metal bumpers.
I suppose if there was a car with pos ground 12V and only the bumper jacks available with no cables, it would be possibles to switch the cables on one vehicle and jump the dead one using metal bumpers. The only thing being that you could not start the vehicle with the crossed cables until it was hooked correctly again.
Then again, being a boy scout means you had jumper cables at all times.