We use some gravity spreaders made by Spread Master. I think they're based in IN somewhere. We get ours thru local bin dealer. The Model SPGD-71c is the middle of the road model (gravity). It'll keep up w/5000 bu/hr auger.

To my knowledge, none of the gravity spreaders will spread to the complete outside of the bin, but you can get a complete fill & not have to worry about shutting off spreader to avoid burning belt or motor. When grain comes up to spreader from filling bin, the spreader merely stops turning & you'll just overflow & neatly fill to the eaves.

To me, they seem overpriced, but so does about everything these days. To their credit, I think they were about the same price before corn went to $5.

http://www.beavervalleysupply.com/sectiona/spread.htm