Lights don’t dim with more electrical devices on?

Dana67Dart said
That would be a great first step.

I would also take car to parts store and have them test the alt, especially for bad diodes. (free and easy)

My 67 would (while sitting at a light) wiggle the AMP meter. I had the alt tested and they reported bad diode. I replaced it and the wiggle is gone.

The diodes convert the AC from the alternator to a form of DC and if diodes are failing the DC is less DC which can result in a flicker etc.

BUT my bet is on the voltage regulator, especially if you did not notice it before the change but notice it now. If that is not the case and it happened before then I would focus on the alternator.

And make sure the regulator case is grounded well to raw metal on the firewall. You need star washers or even a separate ground strap to make sure. A lot of people have charging system issues after new parts and/or firewall painting. Get a regulator from your Mopar dealer. I believe they are still available.