'71 Duster 340 Battery getting overcharged
No, voltage drop is not a function of the VR, voltage drop is a harness / connector / switch problem
FIRST thing I'd do is double double check what you think you found. Also bear in mind the trouble could be RIGHT IN the VR connector itself, either broken loose inside the rubber, or just corroded, loose, not making contact.
So let's double check. "Work" the VR connector in/ out several times to scrub the terminals clean and to feel for tightness. Pull it off and inspect with a flashlight for corrosion or damage
Let's RE check voltage.
Set meter for voltage.
Turn key to "run" with engine stopped
Probe the blue field terminal with one meter probe, leaving the connection normally hooked up.
Stick the other probe directly onto the battery POSITIVE post.
What is the reading?