[C5GTO]

I have a 100 amp alt in my CR and it barely keeps up with the draw. Does OK with the cooling fan on at an idle but if I turn the head lights on, it drops to 12v or below. If I tried to get by with a standard 75 amp alt, I'd be in trouble.

So it's just marginal with 100 amp but I have a 5.0 EFI motor with electric fuel pump and 17" cooling fan. It's a good thing I don't drive the car much at night. In addition, the older Ford alts don't put out much of their capacity at idle. You'll need to use a newer alt for that. My alt guy recommends a newer, compact GM 1 wire. He says these put out more amps at idle than the old Ford alts but you'll need to have it re-clocked to fit in the customary position in front of the passenger side head.

I hope that helps...