Great information - thank you.

Here are more details on the conditions under which I did the earlier tests.

I observed the B+ voltage with a cold engine, and ambient temp was in the high 30s F. I checked it after idling for a while, and the voltage did not move on the B+ terminal. The only known loads were the DRL and radio. I also ran the RPMs up to see if there were any voltage variations and I did not observe any. This makes me believe there was no voltage adjustment out of the regulator between a cold and warm engine.

Last year, I removed the B+ wire to the starter, and built/installed a new B+ to battery cable directly. And built/installed a new ground for the alternator. This nearly removed the voltage drop between the battery and alternator, and everything electrical in the car is much more 'perky'. Since I've observed this B+ voltage change only after swapping out the alternator, I'm confident the wiring off the B+ to the battery is good, as are the grounds.

Is it worth rerunning the test by removing the B+ cable and then testing the output at B+ to the alternator body? I can easily do this when I get home later this week.

Thanks again!