This is Phil for $24 US
https://www.hoonigan.com/products/gates-thermostat-oe-type-engine-coolant-thermostat-p-n-33867-toyota-sienna-3-3l-v6-2004-2006

Where Are You From? Ottawa Ontario Canada

Do You own a car built by Durant? 1932 614 sedan made by Dominion Motors

Wow, the new one even looks like the original unit, but doesn't give a temp rating.

Where Are You From? Fremont, CA

Do You own a car built by Durant? 1929 Durant Roadster & 1931 Durant Model 619 Sedan

Phil you probably already know this but in the Instruction Manual for the Durant Model "66" it says:

The Thermostat is located in the water in-let connection from engine to upper radiator tank. The Thermostat remains closed, preventing the circulation of the water until the engine reaches a suitable operating temperature (about 145 degrees) and then opens gradually until engine temperature reaches 160 degrees when full circulation is reached The operation of this unit is automatic and requires no adjustment."

Also the thermostat that Norm suggested can be found on Amazon for $14.53.

Where Are You From? Grand Junction CO

Do You own a car built by Durant? 23, 26 & 27 Star, 29 663 & 666 Durant

Forum still not working right. Yes I noted that just put Phil's unit number in search and that came up.
As I mentioned to Phil no after market even shows a thermostat US / Can. Online gives you the idea it was mid 30's item and thermostat in 20's was to open rad shutters. Dykes books don't help either what Phil is looking for mind you they have very little info on Billy's cars.

Well getting there Tom. At least we know they were used. 614 I guess they didn't use them as no mention in Instruction Manual. Actually it says .. Motors operate more efficiently at a temperature of from 160 to 180 degrees. Therefore, much better results can be obtained in both economy and performance, if during cold weather a cover or winter front, of some kind is used on the radiator.

Odd thing is winter fronts were not even an option up here on D's but were US.

Where Are You From? Ottawa Ontario Canada

Do You own a car built by Durant? 1932 614 sedan made by Dominion Motors

Thanks Norm and Tom-I will go check it out-Phil

Where Are You From? portland

Do You own a car built by Durant? 1929 Model 60