I've got two sets of mid-mount hillers that I am no longer using. Both sets are for two row set up. They are set for 36"rows but could be adjusted for narrower or wider row spacing (within reason). They are both IH hillers that adapt readily to older IH tractors (other tractor brands - I'm not sure). Both sets use hoes (not discs) which I have always preferred because you can go slowly and build a big hill without as much danger of covering plants. The hoes also build a firmer hill than discs. Both sets include cultivator attachments and various parts to adapt to crops other than potatoes. The hillers are easily removed if you just want to cultivate. The older set has one-way hydraulics and was sold to fit the Farmall H and M tractors. $500 for this set. The newer set has two-way hydraulics. I used it on a 544 Farmall (50 hp)but it will work with almost any IH row crop tractor that has two-way hydraulics. $1500 for this set. Both sets do a nice job of hilling.