Alternator

Go to the parts store you like and buy a reman alternator for a 72 Plymouth Demon 318 non AC.

I'm not being snarky, but what you describe is the run of the mill, reman alternator.

https://www.partsgeek.com/catalog/1972/plymouth/duster/engine_electrical/alternator.html


Since it is an easy replacement item, no need to get the top of the line super-duper 250.00 alternator when a lifetime warrantee 50.00 will most likely outlive you.

Just make sure the pulley is the same OD as the OEM you are replacing.


Now if you have added all kinds of electrical load that's another thing altogether.