no, i do not own a JD disc plow, I just found a picture of a JD disc plow that showed the rear wheel blade.
I have a Ferguson (Bullet) disc plow.
But since you are not going to use the old plow, it will not matter the rear wheel blade is worn down.
However, if you ever do decide to replace the rear wheel disc blade, we got a large coulter blade at the equipment store and placed it under the old blade, centered it and blew the attachment holes out. Using this method, it fit like a glove.
Picture of our Ferguson disc plow attached.