Sorry about it taking a few days for me to get you the info, but I've been a touch busy.
If you look at the diagnostic chart, it really makes it pretty simple. Test the current from terminal (P) of the alternator and see if you have any while the tractor is running. If not, you get to replace the alternator. If your'e getting a signal to the back of the gauge cluster, then you get to replace the cluster. Pretty simple.
If you do replace the cluster, let me know as I said before. I've got a few things that I would like to do with mine and I'll buy it off of ya.
Let me know if the e-mail came through.