I tried replacing voltage regulator, did not fix the problem.
I went ahead and took it apart and found evidence that the stator and rotor had been coming on contact with each other. Also found a loose/broken solder joint on one of the stator wires to the diode carrier plate. Dropped the alt off with a local auto electric guy who rebuilds such things to see if he can source a new stator and/or fix what I've got.