JD 750 grain drill

Hey there, bought a JD 750 no till grain drill a few years ago and was wondering if anyone knew of good spot to find a monitor for it. It came with all the sensors and wiring for the drill so I am only looking for the monitor and wiring for the tractor side. The book says you can use a computer trak 150, or 250. The grass box is awful small and gets frustrating getting on and of to make sure you haven't run out

Thanks in advance for your response.

JD 750 grain drill