I like the Crary chaff spreader. They have a hydraullic flow control valve the the Vittetoes don't have. Plus they are cheaper in price but built the same. Go ahean and check out the Crary spreader out.
The Kuchar parts are definitely worth checking out.We have the complete kit in a 9610 and are very happy with it.If anything at least put some spider bushings in while you got her apart.
We have an air foil in a 7720 and had one in a 7700 before. Real good luck with it, but we have never used it in corn. Beans and wheat were excellent through it.