Had the same problem. Broke my heart to convert; really hoped to stay original but remember 6 is 6 and 12 is 12 and the two don't mingle too well. My stovebolt came with a generator and 8v tractor battery (Exide brand) that you can still buy at Tractor Supply. Had gen. rebuilt but truck wouldn't turn over after being run awhile probably because it couldn't fully recharge the 8v battery. A 6v battery wouldn't work either even after putting in a new harness and big 1 ga. cables. Gave up and turned her over to a kid in the neighborhood who's a hotrodder and used to work at GM's design center. He tells me the truck was an electrical "mutt" meaning half the bulbs were 6v & 12v and the coil, starter and maybe even regulator were 12v. The real headache started when turn signals were added and the headlight switch had to be replaced. Shorts all the place! Should have her back this week so I'll let you how it worked out.