The diode trio short/open should have been picked up during the testing? Question. Was the alternator "bench tested", or while actually on the vehicle? Also, if done on an oscilloscope the sine wave form of the trio can be be displayed to look for raggy wave forms. Is this a model that runs an "integral" or "stand alone" voltage regulator? If a stand alone (as I mentioned earlier) it's ground quality is critical. Last question, does the relative brightness of the battery indicator lamp go up and down with "loads" (lights, heater motor, etc.) will the battery lights output be affected by dimming the dash lighting?