Several things are needed for a charging system to work.

Voltage regulator needs to work.

Alternator needs to work.

Wiring needs to be correct and working.

Since you do not say what year your Dart is there are two possible charging system designs that are possible. 70 and up or 69 and earlier.

On the early system the field gets a switched 12v supplied to it from the alternator. If that voltage is there then the wiring and voltage regulator is good. If not then you need to look that way. As a test of the alternator you can jumper 12v to the field terminal on the alternator and it should charge if the alternator is good. Do not let it run like that for long.

On the late system the alternator gets a constant 12v on one field terminal and a variable ground on the other terminal, if you use a meter to read the voltage on that terminal you will see a voltage there less than 12v, the less it is the harder it is charging, the closer to 12v the less it is charging.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.