Heres how I wire a GM 10SI Alternator on tractors with a battery/coil ignition and remember, it requires NEGATIVE GROUND !!!!!!!
The big rear main alternator output terminal goes to and splices into the wire that used to be connected to the BAT terminal on the Voltage Regulator or Cutout Relay, but basically, the alternator output wires to the Load (NOT battery/starter) side of the ammeter which takes place if you use the wire that used to connect to to the BAT terminal on the Voltage Regulator.. HOWEVER if that wire wasnt already upgraded, when I convert from a Genny to an Alternator, I replace that wire with a 10 Gauge and it runs from the alternators main output up to the LOAD (NOT to battery/starter) side of the ammeter. I also replace/use 10 Gauge from the ammeters other SUPPLY terminal to the battery/starter.
The alternators (if a GM 10 SI) little side number 2F Voltage Sense Terminal gets connected (use a short 14 jumper wire) right up to and with the big main output terminal mentioned above.
For the GM 10 SI's little 1R side Excitation Terminal, run a 16 or so gauge wire from the ignition switches IGN (which is hot ONLY when ignition is turned on) output terminal ORRRRRR the coils high input (NOT to distributor) terminal, and in series with it place a 10 ohm to 47 ohm 5 or so watt current limiting protection resistor . Then in the rare event (likely dont even need a diode if the resistor which I prefer is used) the tractor continues to run cuz of alternator backfeed when the ignition is switched OFF, I add in series a 5 amp 50 PIV minimum Diode. The diode must be wired with negative cathode end to the alternator and positive anode end to the switch. Again, the ratings are not that exact but about any diode over a few amps and 50 volts or so works.
Dont forget to change the battery to negative ground and the coil needs to be wired so the negative goes to ground via the distributor points and the positive gets power from the ignition switch and you have to reverse ammeter leads also if you’re just now changing polarities cuz if its wrong it reads bass ackwards.
Good luck Ol John T in Indiana