Was the rescue from flood damage? I'm wondering why the bad luck with the two previous alternators. Warranty? Anyway... Me, since I don't know how to properly test the diode, resistance, etc. on an alternator, I would remove it and bring it to my local O'Riley's where they would bench test it for me. But something seems really wrong that two previous alternators have failed prematurely for you like that. Good luck w/ it.