I think you will find the number is 3C001-94520
It is the number for my M7040 and I expect they are the same. This number fits 200+ tractor models.
The cap locks open and closes when a quick connect is yanked from the female half.
It is like a friction fit around the coupling.
They are 1/2" ISO 5675 dust plugs. The Kubota part number is 35861-94523. Messicks wants $9.15 for the OEM plug. Aftermarket is about $2 but will look a bit different,