Originally Posted by Torque1st
Some of the old time 6 volt systems were positive ground back in the 50's and earlier. They found out later they got much better ignition performance using a negative ground tho so that is the way everything has been wired since. If some addle brained geezer even older than me wired it back up after a major mess he may have wired it the "old" way.
All Fords were positive ground till 1956.