73 Dart Alternator doesn't show charge anymore.

OK. Two points will unconfuse this.
The battery and the alternator output are connected together at all times.
With the engine off we are reading battery voltage throughout the connected wires.

So in the car we have two power supplies that are connected together.
When the alternator is running, it produces power at roughly 14 Volts.
The battery at best has power stored at 12.8 Volts.
Imagine those volts as air pressure or water pressure.
Which one will the air, water or electrons flow from?