I don't see that Auto-Trac on a combine will do much real good if you can't follow and repeat the path of the planting tractor. And an up front header won't follow the path of a drawn planter. When planters are pushed by the power-unit, then the row units of a planter and header can coincide with the antenna receiver position relationship and you will have true auto-guidance for planting, spraying and harvesting... then invest in it for combines, aka Bi-Rotor at that time. In the mean time, you're real better off with technology similar to a lexion auto-pilot and Cat "wiskers" for corn rows or "laser pilot" on the end of a 36' header, then you can track the previous cut swath without concern about other header widths, curves or other machines running in the same field. My .02 AGV