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Are you saying it is ok to run the newer 80's style alternators on our 74 Darts/Dusters?
They're fully electrically compatible with the older voltage regulators, which is true clear back to the first '60 Valiant. They are not quite mechanically compatible, because different brackets are required. Neither are they fully electrically compatible, because with an alternator capable of significantly higher amperage than the original, you run the risk of damage to the ammeter and related circuitry. This damage can be extensive and catastrophic in extreme circumstances, so to run a high-amp alternator safely, upgrades to the car's main circuit are the common-sense thing to do.Quote:
are we stuck with the stock 35 amp units?
The Mopar alternators our cars came with from the factory were, over the years, made in variants producing from 27 to 80 amps. Quote:
I recently bought a new MOPAR regulator from Summit
Generally not a good pick these days, from a reliability standpoint. Which is a shame, because the Mopar "restoration" regulator (black w/yellow inkstamp) really looks nice. A Standard/Bluestreak #VR125 or NAPA Echlin VR-38 is a better pick. As an aside, I do not understand why it is seemingly so popular to pay Summit's inflated prices for repair parts that are available locally for less, and without shipping costs. 
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in gear at 600 rpm it does drop down to 12 volts and flickers a little
Dimming at idle is characteristic of many — but not all — of the Mopar alternators made before the change to a higher-draw rotor. Don't have that date in memory any longer, think it was in the late 1970s. I can find out. It is generally not a function of having an alternator of too low maximum amp capacity. In fact, many of the higher-amp alternators have poorer low-RPM output than many of the lower-amp alternators. There are also many different pulley sizes, from 2-1/2" to 3-1/2". Larger pulleys aggravate the dimming at idle. Smaller pulleys reduce it. "Remanufactured" alternators are notoriously poorer than rebuilt originals.Quote:
out of gear at 750 rpm I am at 13.6 - 13.8 volts.
That's quite good. Doesn't sound like you have too much of a problem.Quote:
If it is ok to run an 80's unit with the new stock style 70's regulators, Will the higher output alternators stop this voltage drop?
Which "80's unit" do you have in mind? The '89+ alternators (Bosch, Nippondenso, or the Chrysler type w/black plastic rear cover) are the ones that need different brackets and all have output high enough to require a main circuit upgrade to prevent damage. Up through '88, variants of the older Chrysler finned-case alternator were used. These will fit right on as long as the pulley type is correct, but again, some of them have high enough capacity to warrant circuit upgrades.But all of them will work just fine with the car's original type of regulator.
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Will the "ground loop you suggested stop the slight flicker?
It often does.Quote:
This winter when it's 20 degrees and the lights, wiper, radio and heater are on and your in stop and go traffic, what do you suggest?
Depends on how much effort you're willing to put in!