[1990C4S]

The repairs are ongoing. I swapped batteries from my AGM to a known good lead acid, I noticed the charging voltage (when it's working) jumped up 13.8-14.0 volts, which is above what I was previously seeing.

There is no sign of 'wiring' issues, all the connection points are tight and clean, I suspect the voltage regulator is the issue.

The alternator is out, it's going for testing tomorrow. There was a fair bit of 'oil' on the alternator, it's right below the power steering pump, but I have no oil or P/S leaks, so I do not know where it came from. I don't think that's the issue. (EDIT - mine looked cleaner than the one in post #12, so I guess that's normal). Also, the B1 connection to the battery was not supertight, but there was zero sign of heat, and the connection was very clean.

Given that failure on the car takes 10-15 minutes on a hot day, I am not sure what the testing will prove...I will see what the alternator expert says, and what he recommends for a new VR.

PMax - The alternator DID come out through the opening per your posting. It was very difficult (every bit of this removal is difficult) but I think that last time I knew the replacement unit was wrong, so there was no point in struggling to get it out.