I had a problem like this on my Bronco. Don't get mad at the limited details, but here goes. The mechanic I had working on it took a look at it and said that there was something that needed to be removed from the alternator prior to installation, otherwise it would keep burning out. I thought he was full of it, but he showed me a small tag that detailed the process. This was a long time ago, but that was the last alternator I needed. Look into that I guess, but yeah...not a mechanical whiz here. Why do you think I joined FTE!?!!