GM Genuine Parts Engine Coolant Thermostat Housings are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These housings hold the thermostat and is a connection point for the radiator hose inlet or outlet, and may also include ports for sensors or switches. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).