[rexs73gto]

I would check the wires at the reg. connection, if the wires are loose or are corroded it will cause a bad ground concern. Make sure the wires are not loose or burnt through or even have a few of the wire strands broken that will cause a high resistance & cause the reg. to keep in a high charge pattern. Also check the wires on the alt. to make sure you don't have the same problem there. If you have any loose wires it will cause you to have the problems your describing. Or again it could be the reg. itself. I went through 3 of them before I got a good one that worked on my 68 bird. I forgot ,, the brushes can cause that too, so check the brushes out when you get it off if your going to take it to the parts store to get checked out. It only takes a few min's. to pull it apart to check them & another to replace them if there bad. Bad brushes will ground out & bounce on the armature when there spinning at normal speed. Also as they get hot they will make better connection. Check them out just to be on the safe side.

[70gtorag]

The brand new regulator is the old style contacts made by Standard Blue Streak, not transistorized new style. I bought it to replace the factory original one that I thought was not working, but did not completely test it out. The test I performed was with engine running, battery voltage showed up to about 18.5volts. That was at first startup, when the electric choke was on and engine idling at about 1100rpm. Thought I needed a new regulator since it was overcharging, but the new regulator did the same thing with the added bonus of the gen light coming on.
With the old regulator the gen light did not come on during engine running so I presume the alternator and brushes are fine. I did also notice a new humming noise and am now starting to think it is the new regulator. Also, the wiring and contacts at the reg and the alt looked good, but I removed each one from the plastic connector and cleaned them anyway. I installed a ground strap from the reg body to the ground strap connection at the firewall to be sure.
I will run the car tonight and take some more readings then report back.

[70gtorag]

The hum is definitely coming from the new regulator, and is present when the gen light is on. With the car running at operating temp here is what I measured:
Battery voltage 14.0(14.5 during warm up).
Terminal 3 reg 16.0(14.5 during warm up).
Also noticed that the gen light is on bright at idle now and goes out with some rpm. Does this mean the new regulator is no good?