Yep Rotary Screw. Good call Scott. And yeah, guess it might be overkill for any one person shop. On the flip side, it matches your back hoe and dozer.
When I looked it up on line, the ones with 20 to 30 thousand hours on them are described as "mint", or "like new". So I guess they're meant to run a LOT. It'd be perfect to supply a tank at a production shop to run their pneumatic tools and sprayers.
NOT what I need for a mini HVLP gun, but . . . I still want it

I mean, look, these guys got the little version of it . . .
http://www.ultimategarage.com/garageprojects/msi.html