I got my Barton Harness external regulator in yesterday.
It got here fast by the way.  Thanks Barton.

My brown 84, randomly, drained my battery.  I'd have to be sure to 
charge it up fully before a weekend outing.

The plan was to install the external regulator and gain some charging 
voltage.
I put the voltmeter on the alternator and started the bus.
I only had 12.5 volts from the new battery (measured on the alternator).
The old one was boiling a sign of a shorted circuit.
My friend, the owner of the local Napa used an electronic battery tester 
and confirmed the battery was junk.

I revved up the engine and got 13.7 on the alternator.
That was weird.  Something wasn't making contact until the
vibrations caused a good contact.

I measured the voltage on the battery.  It was 13.5Volts.  A .2 drop.
Assumed I was getting a .2 drop over the wires.

I took out the alternator and removed the regulator-brush set.
The regulator itself was warm to the touch.
I started looking at it.  The mounting point was corroded.
This is one the back side of the regulator where the mounting screw
holds it to the alternator.  The contact prong inside was corroded too.
Then I noticed that the large bolt holes were also corroded.  The
ones that hold the alternator to the engine brackets.
Then I realized that I had painted the engine brackets.

So I used drimmel tool with a carbide bit and a air grinder pad to clean 
off the paint and corrosion everywhere.

I put the alternator back in with the original components.
I now have 13.7 volts ON THE BATTERY.

I think I've fixed my problem.  I put dielectric grease on all the contact points.
I did not mess with or touch the brushes or the contacts on the (stator?).

I hope that's it.  This alternator was one I put in about 4 years ago that
I got rebuilt from Auto Zone in KY.  From now on, I think I'll take the
regulator off and put some dielectric grease under the bolt that holds the regulator to
the alternator.