I am new to this forum, I am not a mechanic, and it has been some decades since I last sat astried a Farmall or Ford 8N tractor. That said... after looking at the above post about 12 volt conversion for a Farmall Cub, an old memory surfaced. The Ford 8N and 9N series, if I remember correctly, both had positive ground. The Farmalls I have driven did not, so far as I can recall. Now, the wiring diagram and the described procedure for the Ford could probably be adapted for use on the Farmalls... but I suspect that because of the polarity difference, some things in the wiring diagram might need to be changed. If I am mistaken, I appologize for messing up your forum, but I'd hate to hear about someone missing this and frying an electrical device or worse.