Those must be some really low power lines.  If you're going to plant with it ideally you'll want something that doesn't drift much over time but those signals cost money.  I know Deere stuff so my suggestion is a Brown Box with Autotrac, ATU200, iTC globe.  Maybe $5,000 for used stuff.  You should be able to get by with SF1 signal unless you are controlling clutches.  SF2 would be better but you need the globe unlocked for SF2 and then the signal costs a couple hundred bucks.