Dash lights will not turn off!! 72 dart
1 jumped up to 18.2 volts
This is a regulation problem. The alternators may be contributing to it, but the problem that needs to be fixed is the circuit.
If you have a hand held multimeter you can narrow down the issue.
With the engine running check the voltage at several locations. The question we want to answer is what voltage is the regulator sensing compared to the voltage the alternator is generating?
Measure: Voltage at alternator output compared with voltage at alternator feed (blue wire), and/or compared with votlage where the blue wires are joined at the ballast resistor.
Those are the two closest locations in the curcuit to the regulator's sense terminal.
If there is a voltage difference between the alternator output and the field terminal, then some or all of the problem is in the circuit.
If the output voltage varies with rpm (increasing together) then the regulator is damaged (full fielding).
Replacement alternators can contribute to the problem when they have been built with rotors that draw twice as much current as the factory intended. I suspect that many regulators can not handle the higher field current. Higher field current also magnifies any resistance in the circuit wiring.