Alternator question

Thanks guys, I'm at work, so I will answer as much as I can.
Bear with me here. The alternator is approx 3 yrs old. Bought from Canadian Tire, I can't find receipt to verify 100% what application I gave them.
I know that it was a direct bolt on, I did no mods to it.
Del, yes I remember the "burnout" from 2012...like it was yesterday lol.
I replaced the VR last year(black case upgraded guts) see earlier pic, or 2 years ago.
A quick rundown of how I got to this point. Driving home from Moparfest, doing approx 65 Mph, all of a sudden no power at all, basically car shut off. Quick 3 lane change, pull over. I wiggle this n that, turns over but no start. After 1/2 hr of trying a couple things, it fires up! Starts but VOLTMETER(Mad amp bypass done) is reading approx 11.5 volts??
Get back on highway.....65 MPH. Keeping an eye on all the gauges. Volt is gradually creeping up to 15 Volts. Took about 10 minutes to get to 15.
Got about 20 minutes of driving, then no power again.(I'm getting good at 3 lane changes by this point).
This time no start....2 1/2 hours on side of the road trying(Im a stubborn prick).
Towed home.
Next morning I wake up, swap ECU. Starts right up.
Pull around to back yard to see if I can figger it out.
Wont start again. I tried "tap test" with key on everything hooked up except the electronic dist plug, no spark.
I threw a cover on it walked away and went fishing instead....more fun pouring catching Walleye and Bass lol.
ALL SUGGESTIONS WELCOME lol
67 Barracuda, MP elec ignition, Mad bypass, VR is old style with electronic guts( I believe). Alternator is single field old style( I believe)
Thanks again guys I plan on tackling this Monday and Tuesday, so any tests/results I can do I will.
Thanks!

You likely are on the wrong track with alternator/ charging problem, Steve. With a car an a "good battery" you should be able to disable the alternator and still drive the car........even with lights........at least 1/2hr to an hour. In the daytime a LONG time.

You likely have trouble in the bulkhead connector.........ammeter connections........ignition switch connections.......or cough gag.........the welded splice in the harness. You say, "no power" did you have anything at all? If not, then it's not the ignition switch.