I have single alternator and it is on the drivers side. The only thing that's been replaced so far is the alternator. I will keep an eye on this belt. I believe if I would have had a second person I could have gotten the 100 & 5/8 to go on but I figured if it was that tight that may not be good either. If this one stretches I'll go for the 100 & 5/8 and get my son to help me.