I go on E-Bay. Find the temperature value, normally open or closed, whether two pin or grounding and the NPT size. It isn't hard and beats a dealers price.
Keeping the Rad clean on My loader makes a HUGE difference. Blowing it out helps a bit, but washing it out makes a big difference.
Getting that heat from the hydrostat through the cooler, in front of the radiator makes it hard to keep the engine cool.
I do go to a Kubota dealer to get engine parts and filters for various other machines with Kubota engines, because those dealers just invent their OWN part numbers and charge even more than Kubota. Like what STEINER wants for (Kubota) oil filters. Unfreaking believable! But that's their right to charge as they please.