The 56 Ford electrical system was the last one to use positive ground, and yes, it was 12 volts. in 57, all the automotive manufacturers standardized their electric systems at 12V negative so aftermarket accessories like radios could interchange. I've got an 8N back in the weeds that will come up as a restoration project one of these days, but I'll probably go with an alternator and my own adaptation of an electronic ignition. It's relatively simple to use a magnetic trigger from any 4-cylinder electronic distributor to cycle a GM or Ford module, and you've got all over-the-counter parts, not somebody's ridiculously expensive proprietary system. I don't think anybody could run fast enough to give me a Pertroinix. Does yours have the pancake-style distributor mounted on the end of the camshaft? If so, your choices for an electronic trigger might be somewhat limited. That one's similar to the flathead V-8 distributor used up to 1948, but the tractor distributor has a 4-lobe cam instead of 8.
Jerry
