Going off of memory there are eight (8) options for the control valve.
with that said, take your pick. They should all interchange, fittings, hoses, linkage should all be roughly the same. One difference would be in the float detent-I do remember that specifically, and if you don't already have it you won't miss it if a new valve don't come with it. Or if you don't have it and the new one comes with it, you might like it.
Should be able to rebuild the valve assembly if it's just leaking, UNLESS the bore and/or spool are worn significantly, which I would personally consider a rarity. "Rebuilding" meaning if you can't get the seal(s) you need from Kubota, you may be able to source them from a hydraulic repair facility. There aren't too many around here, 2 that I know of in a 100 mile radius, but they both stay very busy and are highly regarded. Might be an option for you if you have something local to you.