Sounds like you're set. They probably ran slotted grates with the small wire concaves for small grains like wheat. The slotted grates are smooth on the ID so that they do less damage to the straw and provide agitation to the crop to give extra separation. For milo you will want the large wire concaves and keystock grates. For corn lot of people take out every other concave wire. In soybeans, if you experiment, I bet you can find all sorts of combinations that work. We run large wires with the first 1-1_2 concaves blocked off, two slotted grates, and a keystock at the rear. This combination does a decent job in everything we cut, but we don't have corn.