Well, you either hook 'em up to pull through a shroud (shroud attached to a heater core):
Or you hook 'em up to pull air into your enclosure and let it vent out through the heater core (so the entire enclosure becomes the shroud).
The impeller in the picture is smaller than the one at am sci and surplus - but those will still fit in the same area a 120mm fan will (only a good deal thicker). If you wanted to put a couple of heater cores in the same box, they'd both get fresh air if you ran it this way.
They aren't quiet, but
man they have some suction.