I have a 1985 Cadillac Seville with the 4.1 engine, I am looking for a part im kinda confused on what it is called as far as i know it is called the thermostat housing, but when i ordered a part by that name from auto zone they gave me the water outlet that connects to the thermostat housing so im not sure i need the part that the thermostat sits in, the part goes between the engine, the water pump, and the top house coming from the radiator, so what i need to know is what EXACTLY the part is called and where i can find it because i have called every auto part store in the area and most the junk yards any info would help

I need either to find someone who is parting the same car or where i can find the part, i live in melbourne florida, thanks