If it had the 105 amp alt on there, and then you put a large case alt on there, it will kinda work at first. The pulley is in a different location and the large case belt is 3/4" longer. You can get it to fit, but if its the smaller belt it will put more tension on the belt. There are always threads about this, where it is harder to start, and it will start to squeal (anywhere from a few hundred miles to a few thousand). You should be able to easily pull the part number off the belt and check it on rockauto or somewhere else to see which belt it is (105 alt, or 130 & larger). If it is that, its a $20 belt now, or a new belt, new tensioner, and a lot of wear on your new alternator IF its like that and left that way.