All kidding aside.....I dont know. I assume the casting is the same and can just swap the spools, and the stuff on the bottom (can). But you get into detents, springs, little ball bearings, etc. It can be a paint. But I would want confirmation from baileys first if the switch is allowable. Some spools are actually precision matched to the bore.....others are 100% swappable.
Not sure what I would do if all I had was a third function. Cause just cycling the valve with tractor off, like when removing the loader...just don't work.