Sounds like something is "full fielding" the alternator all right.
Do some troubleshooting
1 Get a meter and check running voltage at a good fast idle or simulate "low cruise." should be 13.5-1.42 or a tad more
If it's overcharging, first yank the connector off the regulator and see if the "high charge" goes away. If it does,
2 It's time to see if the regulator is getting good solid voltage and good solid ground. DO NOT skip the following steps
3 If the ground on the regulator is poor, it will overcharge. Again, with the engine simulating "low to medium" cruise RPM, do these checks first with all loads off, and again with heater, lights, on
4 Stick one probe of your meter DIRECTLY onto the battery negative POST (not the connector) and the other probe DIRECTLY onto the regulator case You are looking for a very LOW reading, zero is perfect, no more than .2V (two TENTHS of a volt) If more, this indicates a poor ground, and you need to go over the ground system.
If the battery is up front it should be grounded directly to the BLOCK with a jumper(s) to the body. If the battery is in the trunk, and grounded to the body, you need a BIG jumper from the body/ frame to the BLOCK. IF you are getting readings above .2V in the test, you need to ADD a jumper from the block to the body. No10 min. Bigger is better.
5 Now do the same test on the HOT side of the circuit. The regulator gets power from the "dark blue" "ignition run" circuit, and this can get "dropped" on it's way from the battery, through the wiring, through the bulkhead, the harness, the connector at the switch, IN the ign switch, back out the connector, back through the harness (dark blue) BACK out through the bulkhead connector, and to the ignition system, regulator, and alternator field.
THIS DARK BLUE not only supplies the regulator field current IT PROVIDES VOLTAGE SENSING to "tell" the regulator what to do.
SO
6 Stick one probe of your meter directly onto the battery POSITIVE post, the other probe as close to the regulator as you can get. This will probably be the "dark blue" connection at your ballast resistor. ONCE AGAIN with engine running "low / med cruise" you should see NO MORE than .2V If so, you have a VOLTAGE DROP in this harness circuit path.
7 If this checks out and the voltage at the battery is WAY high, it's probably a bad regulator. NEW does not mean GOOD
8 If up at the top, when you pulled the plug off the regulator, and it KEPT ON CHARGING, one common problem is rebuilt freekin' alternators. It is common with rebuilders to MODIFY a 69/ earlier frame and put a hacked -- up modified brush holder in to convert the thing to "isolated field." (They are NOT "dual field.)
Sometimes when this is done, the original grounding brush !!! for the 69/ earlier alternator gets left in there, OR one of the brush holders breaks and allows one brush to ground.
IF THIS BRUSH happens to be in the green wire circuit going to the regulator, it will "full field" and charge all the time.
