74 dart sport won't charge

No I think that's OK. If it seems to be charging run one last test. Get the battery charged up and normal, and engine warmed up. At a fast idle or better, the battery should show no lower than 13.5, no higher than 14.5. Optimum is 13.8--14.2.

If that shows OK, turn on the light,s heater, and see if it maintains that at simulated "low cruise" RPM. Don't forget to verify the V belt is properly tight.

Make absolutely certain the VR is grounded, mounted tight