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I'm no expert, but if the current 6V system is positive ground, then AFAIK it's going to have to stay positive ground after 12V. Otherwise all the gauge polarity etc will be backwards, from what I recall. I know that the tractor Dad did is still positive ground, but it's now 12V.



Nope Nope no, no

You want the 12V system NEGATIVE ground NO MATTER WHAT

This is because this is the "world standard" and any other accessories you buy (electronic) need to be 12V negative, and also because almost ALL 12V systems from the getgo were negative. (There were and maybe are a FEW industrial or trucks that are 12V positive ground--these are few and far between)

So far as gauges, just reverse the leads on the ammeter. Most gauges, like temp and fuel, may or MAY NOT need to be reversed. Some don't care as per polarity as they are "hot wire" gauges

THE REALLY important thing for delicate gauges like temp and fuel is to make sure you get the correct voltage drop. I'd leave these unhooked until you get everything else working, then deal with them.

Anthing like heater / wiper motor and probably clock, don't care. Likewise starter/ solenoid

Good luck finding a positive ground alternator, and yes, they do exist