One man's trash.......

I scored a fan just like OP's from a local university. OP scored big, those fans are great because they'll cool you when you're standing.

When I see tossed residential furnaces, I grab those squirrel cage fans. NOTHING moves more air for the size, and they're great if you're in a hot garage under a car, because the dirt that falls doesn't land on you, it blows away. Tilt em back a little and they'll blow a ton of air up your shorts, which has multiple benefits. Wire em up right, and you can even select speeds on some of em.
An A/C guy I'm friends with mounted an old A/C squirrel cage blower in the ceiling of his garage with a thermostat attached, and put intake vents in his garage door. It draws cooler garage air into the attic and pushes it out through the gable vents. We get 100° summer days which makes it 140°+ in an attic. Any time you can draw cooler air up into the attic in the summer the better off you are.