73 Dart Alternator doesn't show charge anymore.

Figured I'd give this thread a bump to see if I can get some further guidance with troubleshooting, I've had abit of issues with my electrical system since I replaced this alternator, granted I replaced the alternator before the wiring harness, but now I'm constantly chasing down electrical gremlins, sometimes it seems the alternator isn't providing enough charge, but at the same time after a cold start it'll sit on the +20 line on the ammeter for a good couple minutes, and from what I understand that's not healthy for the wiring. Today everything coming off of fuse 5 (running and parking lights, door buzzer, horn) stopped working, don't have a replacement fuse but I don't have an explanation for why the fuse may have blown in the first place.

I have a Retrosound radio I installed recently and it usually works fine, but sometimes after putting the vehicle into gear the radio will turn off as if it doesn't have enough power before turning back on once I start driving.

Could all this just be a bulkhead connector problem? All the engine bay side bits were replaced with the harness, but the connector itself is still the old one. The voltage regulator has also not been replaced yet, could also be the issue.