74 dart sport won't charge

You are welcome. Here's what MIGHT be happening. You might have an unknown heavy duty alternator, or one with a partial short in the field. In other words, the alternator might be blowing up regulators

To test this, do the following...........

(First what brand and model multimeter do you have? Does it have a heavy amperage scale like, 10, 20A DC?)

Set the multimeter up for high amperage, and disconnect the VR connector. Turn the key to "run." Identify the green wire and hook the multimeter from the green to ground. You are now measuring field current. It should show around 3-4 A If it shows more like 6 or above, then "we" might have a problem

One of the members on here found a better VR that can handle heavy current.