adapted jd 6600 spreaders on to the old white 9700 combines, had them ow enough to pick up the chaff, and angled slightly up in the rear, built a guide vane on the front sides to direct the flow and made the pans larger diameter. we were in 50 ft swaths and the spread was around 35 ft . also had angled risers on the pans to grab the material and help accelerate it. minimal hp as opposed to a chopper and virtually no maintenance. the vanes were about 2.5 inches tall and we had several holes drilled in the pan so as to be able to change the angle of the vanes readily, although once we found a sweet spot it did not change much if ever. the secret to the spread is the rpm of the pans and they did have rubber belt strips that were outside the pan 6 or 8 inches.