Over charging
Two things to diagnose:
1. Damage caused by the power supplied at high voltage.
2. Initial cause of voltage regulation being bypassed.
Uncontrolled voltage occurs when the alternator's rotor is supplied power and the brush that should go to the regulator's control (via the green wire) is connected to ground. However there are other ways high voltage could be allowed by the regulator such as when it gets incorrect voltare information.
1971 Plymouth duster 340. Stock. Only changes a set of autometer gauges. Everything worked fine till 5pm Saturday
Autometer gages. Are those in addition or instead of? I ask because old school set of 3 gages under the dash often included one ammeter, and in more recent times a lot of people add a voltmeter.
I think Del's post 4 is a good first step even if it seems redundant to your initial tests.
Replaced the battery and checked the charging system and it was pumping out over 17v.
It may be helpful to consider that is more like pressure, and ampreage is flow. So the charging system was producing over 17 Volts. The amount of curent it was pumping out is what ever was shown on the ammeter, plus whatever was going to the ignition and alternator's rotor. Factory stock, that would be about 5 amps at 14 volts and a more at 17 volts.
This may seem picky, but I think understanding it is helpful in diagnostics.
The blue and green field wires even with the ignition off have battery voltage. I know that's not right. Wire shorted against power?. Ignition that is supposed to power alt works properly.
Not sure what you mean here by "works properly" if there is power in the blue wires with the key off.
Maybe recheck as suggest in post #4
Voltage took out my tac, haven't check everything out yet.
High voltage could take out any electrical item that was switched on.
I'd examine all the connections and wires from the alternator output to anything that was drawing power.