For the shroud to do it properly you should move the old one down and cover up the gaps at the top and at the bottom... that would be the easiest way if you ask me. Otherwise your talking about cutting it in half and then filling the gap between the fan and the top of the shroud and filling the gap at the bottom of the shroud and fliing the gap between the two pieces. Or you could make a custom fan shroud. Or you could get electric fans