Voltage Regulator Malfunction???

VR's are temperature sensitive.

You need to check voltage when the engine bay is warm, the battery is "normal" temperature and the charge is normalized.

Also MOST these girls if they have not been improved, have VOLTAGE DROP in the ign1 "run" ignition line, which is the line from the key that powers ignition system and VR. This occurs both in the ground circuit (more rare) but mostly the hot side, in the bulkhead connector/ ammeter circuit, and ignition switch and connector

TO CHECK IT

Turn the key to "run" with engine stopped. Stab one probe into the battery + post, and the other connect to the VR IGN lead. You are hoping for a very low value, the lower the better. If it's more than about .3--.4V (3/10 of one volt) chase through that circuit and find out why

Also check the ground side. Run the engine on high idle, and check this first with all accessories off, and again with heater, lights, etc powered on. Stab one probe of your meter into the top of the battery NEG post, and the other into the mounting flange of the VR, HARD. Again the lower the reading the better, zero is perfect