Kubota has an industrial engine support site and that is where you can get all kinds of Kubota power.
Your tractor model and SN plate will tell the engine platform, such as "Z", "V", "D" etc and the liters of displacement. That is the only way you want to refer to an engine at the Kubota industrial power site. They can do NOTHING with tractors due to dealer contracts BUT all the Kubota power they can sell and their prices are great.
I got all my Kubota parts for my Z 750 in my L175 and the prices blew away even the cheapest after market I could find.
Good luck.