Finally available again from TrackBoss, these are identical to the now discontinued, famous Robert Shaw thermostats. These are correct for Cleveland based engines.

If you have a 302c or 351c, make sure you still have the OE restrictor plate fitted. If yours is missing, we stock replacements also. The 351M & 400 have the restrictor cast into the block.

The Trackboss 333 series thermostat has the distinction of being the only available thermostat that would accommodate the 351 Cleveland Controlled bypass system*.  A 351C provided greater water flow in the engine for a faster, more even warm-up without creating hot spots (particularly in the valve area). The bypass design controlled the water flow and temperature with less cycling and increased the flow to the radiator for improved cooling performance. It was an ideal solution for overheating 351C found in Mustangs and hot Panteras. 

Available in 160, 180 and 195 degree temperatures.

*The 400 and 351M had this feature cast into the block and did not utilize this brass bypass insert.