you can use the BVM fan in most 5" applications with just a little fabricating of the inlets, My idea is to take a piece of hard foam "beer cooler thickness" cut it out in a circle to match the 5" inlet, then cut the center out to match bobs fan. Then "ramp" the difference by sanding, so the air wont be distrubed any more than is absolutley needed and epoxy it into your inlet. Just a thought, probably someone has a better way. russ