Looks kind of like you only had three studs on there to begin with.?.
Good idea with the locking pliers to get it mobile and to a place to work on it.
Glad it didn't role over on ya when she came loose. My dad had a kingpin break while moving round bales with his front end loader. It damn near rolled, would have been really bad.
I've never worked on a Kubota but most wheel studs are pretty easy to replace.