A buddy of mine has a restored 54 Ford COE (239 Y-block) with 6v positive ground electrical. He's having electrical issues (battery drains, generator not charging, no fuses, most of the wiring is routed through the ignition switch to name a few issues) that he's asked me to troubleshoot and work on for him. Because my mind automatically thinks in terms of negative ground, I'm tempted to re-wire the truck with negative ground and add a small fuse block etc. (the wiring harness is new and was replaced by someone else). Is there an advantage to negative vs positive ground? Why did all the major car mfg's go to negative ground shortly after this time period?