GL, you should run the 10gu wire to the ammeter and the other side of the ammeter to the battery with another 10gu wire.
Sounds like you have a two terminal plug on the alternator also?
Terminal #1 is the idiot lamp wire and is switched with the ignition if you want to use it. For a tractor, you should probably hook it up as without it, you have to rev the motor up a bit to get it to "kick in" and start charging.
Terminal #2 to the battery +terminal. This is the sense wire and is required for regulating the alternator. You should measure it AT THE BATTERY - makes a big difference on the performance of your charging system.
Have fun!
