atwood hot water heater thermal cut off connections

I am not sure which of the mating connectors is gone but...

IF it is the ECO, you can get a new ECO at most any RV store or Camping world

If it's the connector on the wire... Any Radio Shack, Auto parts store, Hardware store, Lowes, Home depot, electronics stores

The ECO is nothing more than a disc thermal switch (Thermostat) that is under the foam plastic,,, The T-Stat is the exact same thing only with a different temp setting, You can get both of them at any RV dealer.