We want to get it but haven't yet this year due to cost. We had a few fields mapped and variable rate fertilized by simplot. Hoping to get the entire trimble/ag leader setup next year so we can do it ourselves. We have a valmar 40 foot air spreader that runs the rate like all spreaders off the tire. Looks like all I need to do is remove the transmission and drive tire and put a hydraulic motor there. Get a shaft speed sensor, a oil flow rate control, and calibrate it, should work good. The hard part will be calibrating it to get the oil flow rates right, but I think the regional GPS guys would come help us with that. They sounded interested anyway. This is only the second year that an RTK tower has been available from the dealer here, so GPS is just getting adopted by the row crop guys. Some experimenting with strip till and stuff like that too. That works less here than other places though because you still have to work some of the ground first, since we rip in the fall to prevent wind erosion.