Re: which coil mfr. to trust?
I have used the 12SI 94 ampere GM 3 wire alternators, with the BATT to terminal number 2, 14 gauge jumper wire on just about everything, including my friend's fork lift, for over 30 years, and not one HEI or MSD module failure, including the ONE unit that stuck the regulator to 17.0 volts. All that one did was run 85 miles back to the shop, where we replaced the bad brand name regulator with another, and it was fixed, NO HEI module failure, nor coil failure, either.
There is even one bunch of HEI people that run their units at 16.0 volts, and they don't have module failures, their coils go away regularly, but their other HEI parts run just fine.
A historical FACT about the internally regulated 3 wire alternators. When these came about, there were TWO versions, road vehicle, and farm and industrial use. Differences were strictly as how the regulator was excited in each.
The 3 wire has a number 2 side terminal, and in EVERY vehicle they were installed in, like all the dcars Ihave that have them, that number 2 wire feeds back up the wiring loom, beside the large BATT wire, and merges with it, about 8 to 10 inches back from the alternator. This can be duplicated quite easily with the 14 gauge jumper wire, externally, between the BATt and terminal 2, done, now, home made single wire.
The farm and industrial version had that terminal 2 jumper wired INSIDE the alternator, it was designed as a single wire from the get go. THESE particular regulators, internally connected, are what every after market "single wire" GM SI alternator uses.
With this, the number 1 terminal isn't an exciter, it is simply a charge indicator light terminal for uses that have a charge light in place.
So, internally, externally, make the jump, done, single wire works. IT'S JUST THAT SIMPLE. BTW, my 1986 GMC Safari van with 4.3 V6 and factory 5 speed, has a later CS series alternator and voltmeter stock, and the ONLY wire going to it is the large BATT wire, no jumpers on it, either.