Art, thanks for the wiring diagram but I'll have to admit, it might as well be in Chinese because I just can't read these things. Nothing to do with your diagram, it's on my end. My grandfather ran the electrical works for a country. My theory is that he used up all the knowledge available to my DNA regarding electricity and now I'm left brain dead on the subject.

Cute story, but I don't agree. Left brain or right brain, you will need to acquire some basic understanding of electricity to permit DIY maintenance of cars in the computer age. Part swapping will only get you so far, as you have found out.

My alternator came off of a running vehicle and was functioning at the time. Is it a known good? I suppose it is questionable but I could argue that there is no possible way on earth to be 100% sure it is a known good, even a brand new one. I verified that the brushes are well over 5mm in length.

Put it back on said running vehicle and retest. You had the regulator out to check brush length; are you that certain it is back in place and making good connection?

Ground was checked with the meter, visually, and with a good tug, how many ohms should I be seeing for an acceptable ground?

"Ohms seen" are irrelevant to acceptable ground in a high current circuit. Your ohmmeter cannot come close to qualifying that ground. NASA's ohmmeters wouldn't either. The good tug and your eyes is what you will use. Then, when running, a voltage reading referenced to the battery negative post, to verify.

I don’t recall there being another spade on the back of the alternator but considering that this issue arose without me moving any wires around I think it’s safe to say it is connected to the correct spade.

I'm lost here too, but that certainly is the air gap between us. You can swap alternators without rewiring? Or are you now saying the alternator worked for a while and suddenly quit, yet this is a "known good" unit. I'd like to help, but I'm missing some important fact.

I checked the belt tension and verified that the alternator is in fact turning, I’ll have someone kick the RPM’s up while I check for a charge.

The RPM of the engine is not the question. It is the RPM of the alternator rotor that is important to generating electricity. The problem won't be checked by getting someone to goose the accelerator, which you could do unassisted by reaching for the throttle spool. Proving this disconnect, which can occur at the belts or with a slipping harmonic balancer is not easy -- that's why it is on the last of the suspect list, and tends to fool some reasonably experienced folk.

I have found that D+ has continuity to ground between the gray connector on the firewall and the instrument panel, that sounds like a short to me, correct?

What is continuity?

A very simple way to substitute for the "pre-excitation" circuit -- that D+ wire through the instrument panel -- is to remove the small red wire from the alternator and connect a dash light bulb (any small 12V bulb) between B+ and D+ terminals on the alternator. Make a test light from such a bulb with clips on it. After you've fixed your alternator, you'll find this the handiest electrical tool you own, and it won't lie to you like your DMM does. Add a few other items you can make from junkyard parts, and keep it in your glove box.


--
Art Benstein near Baltimore

Fruit flies like a banana. Period.