I built mine. Made a boom to bolt to the front weight bracket (two bolts) of my JD 425, JD 445, JD X485, and JD 455, that has 4 spray nozzles. Ball valves make it so one to four can be on for spraying. 30 gal tank is on a lawn-trailer chassis for easy hook-up to the drawbar, and it has a Shur-flo 12 v pump, a filter, a pressure gauge, and a return line to the tank. Added a connector into the rear tail light for power, so dash-mounted lights-on/off switch is used to turn the pump on and off. Quick and easy.
Bought parts at local tractor supply house, similar to TSC.