Having a transit bus with limited spaces to mount a 10kw genset, I created a gen cabinet next to the driver's seat (like a front engine). The space was just big enough for the genset, but not for the radiator. I made my own radiator fan out of a single inlet squirrel cage blower from Graingers. I sized it to just fit under the floor (have 22" height available). It uses a 1/2hp 2spd totally enclosed fan cooled motor. High speed for during the day and low speed for nearly silent operation if needed at night (like hot summer night boon docking). For ventilation of the cabinet I used an 8" inline bathroom fan and split it into 2-6" ducts. The generator is mounted with the engine facing back. The ventilation ducts blow in right on the alternator and have two more 6" screened (to keep the critters out) ducts at the back. It's extremely hard to make a blade radiator fan quiet. My generator is much quieter then Onan's "quiet" generators. Remember-there's no such thing as a too quiet genset. Good Luck, TomC