My alternator just went out again on my 1991 F-150 300cid 6 cyl. Luckily ive got a lifetime warrenty from NAPA but Im not sure how much longer they will keep replacing them. I had it checked out at a shop last time and they found the alternator to be shorted out. They checked the electrical system for a drain or short but found nothing. I replaced the battery after the second one went out. Im getting about 6 months out of each alternator. Has anyone else had simular problems?? Anyone with some ideas for me to check out?? Thanks!

I flatly refuse to purchase any "rebuilt" electrical parts.

If I need a starter or alternator fixed, I personally take it to a local (very reputable) rebuilder, or purchase a used one from a recycler. I have equal luck either way, which I'm sorry to say is apparently better than yours.

Check the wiring harness from the alternator, the one that plugs into it. I played musical alternators for a while before discovering all I needed was a cheap plug( available at the parts store)