It's baaaack! HELP

OK. As I posted earlier, I decided to put a new ign. switch in and bypass the ammeter. Figure my "problem" had to be one of these things, by process of elimination.

Today I put in the new ignition. Not that bad, just a bit tedious. The old one didn't look or feel like it was bad. Hook up the battery, check turn signals, flashers, dash lights. All good. So I fire it up. Purring like a kitten. Rakety rack. Sounds real good. I already disconnected the tach to eliminate that, so I'm watching the ammeter. All of a sudden it's all over the place, pegging from full charge to complete discharg. Then it dies. Just like before, no restart until I turn the key off. Fired right up and now showing a discharge while running.
First thing I did is pull the pos batt cable off and it dies. Not charging. 2 month old alternator.

While running I'm getting no charge. The big terminal on the alt is showing 12.5 volts, the battery showing 12.8. Both field terminals show absolutely nothing.

Could this be the ammeter? I sure hope so. I thought I was stumped before, but now I'm pullin' out hair.

I have 4 days to fix this %^$# thing and I was really hoping it was the ignition switch.
What should my next move be?