Thermostat water neck or 'Connection - Water Outlet' as it is called in the Ford manuals. Fits 1970-73 351C or 351 Cleveland engines as found in 1970-73 Mercury Cougars and most all other Fords with the 351C engine. Cast aluminum housing.
*Note - original water necks were cast iron, this is cast aluminum.
Gasket not included. Find it here.