I bought an alternator a while back, and it worked fine, for a while...

Volts drop to 12 at 3300rpm cruise. Run the fan and the lights and the wipers and watch the volts creep downward. Kill all the loads but the engine systems, and it creeps back up to 12.3 and NO higher. Finesse my hand down to the back of the alt and play with the plug. Works fine, for a while...

Volt drop again, same as before. Autozombie clerk lays the alt tester on it, and when he does the battery test, the engine dies from no 'lectrons. Bad battery, he says. See, it's always the battery is bad first at AutoZombie. New warranty battery. Charges to 12.3v at speed. Play with the plug. Nada. 12.3v.

On the way to the real auto parts store. Volts go to 16. Turn on all the loads. Volts go slowly down to 13.5 (normal city). Volts stay at 13.5, for a while...

Get in truck today. 12.0v at speed. Turn off loads. 12.1v. Drive 2 more miles. Whambo, 16v again, for a while.

Now it's running 12.5 or so under heavy loads, and 13.5 under light ones...

Autozombie clerk told me at least one of the diodes is bad. I don't think this computes, but 'lectrons and me aren't the best of friends...

Any of you 'lectron geniuses out there? My best guess is either an intermittent fault in the alt plug circuits, or a failing regulator.

Didn't somebody post about DO NOT do the HLA rpm fix on a Gen2 ??????. Something about voltage spikes straight thru the heart of the reg??