I would consider any aftermarket unit as long as it is plug and play.OEM would be a LA681 or LA682
The chances of finding one of those complete, well lets just say you have better chances of hitting the lottery.
You might want to look at aftermarket like Woods or Koyker.
What Tractor do you havePlug and play might be a little complicated when it comes to a 25 year old tractor.
I got lucky for mine and found a complete take off unit.