here's another thought.........when I first got into mustangs in 98, same problem with alternators..........then somebody off another website mentioned something I tried and I never replaced another alternator unless it was bad when I bought the car..............get a battery with higher cranking ams (cold cranking amps)not the just barely get you buy one they advise............the guy told me they are always charging and discharging and it's as though the alternator is "overworking" itself. Does it make sense, I don't know. Have I owned 41 mustangs since 98 (3 at the moment) and never replaced another alternator..........yes. worth a shot.