That's also one way to determine what Mr Gasket & others are selling ... search which motors the thermostat fits. The 333 series fits 351C, 351M and 400 only. And a thermostat that fits 289/302/351 Fords, small block Chevys or small block Mopars will not work properly in a Cleveland.
Ford has used the Robertshaw high flow thermostat in many applications since the 1960s, and I believe they still use it today. They all look the same from the top, but only the one designed for the 351C has the little 11/16" flanged button on the bottom. Its a small subtle difference that many people don't understand. This thermostat is unique to the 335 series motors (351C, 351M, 400) and no other motor uses it.
Even Ford has sold the wrong thermostat over the counter in the 1970s! They actually boxed the wrong thermostat in the box of the right part number. Check out techincal service bulletin number 9, page 11.
My advice is to use the 333-192 thermostat. The original 351C thermostats were 192 degree thermostats.
...