Boosted Falcon

Can anyone advice on a NB1 charging problem? It’s my track car and has a new battery, had the original alternator checked, replaced it with a known good NB2 80amp and have installed a rebuilt AC Delco unit, cleans all the grounds, swapped ECU’s with a known good unit, check all the fuses. According to some info I have found one of the leads to the alternator should have 12v when unplugged and the engine running and when plugged in to the alternator it goes to 1.5 square on one wire and 10v square on the other. Well I don’t have 12v to the alternator plug when unplugged.
I have been messing with this on and off for a week and know it is something simple I am missing.