My dad runs a 10 row, 22" head in NC Iowa on a 1660 that had some of the 1666 updates from East Moline, but not all. It handles the head fine but have to add 3rd cylinder and weight to the back end. We have 6 weights there I believe but could use a few more. Most of our fields are pretty flat but we have some hills because of creek but the rows are short and don't get the hopper too full.