I need to know what the unit is called that the thermostat housing connects too!!!!

I would get a second opinion. I don't know your car, but in most cars, the coolant tank connects to the radiator, right under the radiator cap. I don't see what that has to do with the thermostat housing either.

Assume you are asking about the thermostat. You can find it by tracing the radiator hose to where it connects on the intake manifold. The piece it connects to is the thermostat housing. The thermostat lives inside that housing.

1. Disconnect the negative battery cable. 2. Drain and recover the coolant. Refer to Draining and Filling Cooling System. 3. Remove the air cleaner assembly. 4. Disconnect the radiator hose and electrical connectors from housing. 5. Remove the heater hose from the coolant outlet housing (1). 5.1. Remove the exhaust heat shield. 5.2. Remove the nut from the exhaust manifold. 6. Remove the bolt which retains the power steering pump and set the bolt aside. 7. Remove the coolant outlet housing bolts. 8. Remove the coolant housing.

follow the water inlet pipe to water pump the thermostat housing connects to water pump this is for 2.4l engine you have to remove exhaust manifold heat shield.you will see the water inlet pipe going to water pump inlet thermostat housing.for the 3.1 engine follow top radiator hose to thermostat housing you have to remove air filter air duct and filter housing , you have to remove throttle body unit with coolant hoses, you have to disconnect accelerator cable, transmission down shift cables at the bracket bolts to throttle body.once you remove throttle body unit then you can see and remove the thermostat housing to replace thermostat.you need to buy new throttle body gasket,and new small coolant hoses connects to the throttle body unit.have extra gallon antifreeze dexcool on hand.

The thermostat is a black plastic water outlet housing connected to radiator hose. when replacing the thermostat the whole housing is replaced.

water out let housing,,

If it's where the upper rad hose connects, it's likely the thermostat housing. Some vehicles are designed with a plastic filler neck that houses the Thermostat, upper rad hose, and filler neck in one unit.

it goes inside of the housing unit. but when you put the housing unit on, the stem should be pointing to the engine

You are right indeed it is called a thermostat housing.

It might be sealed with a gasket, or o-ring, or it might be sealed with silicone. The small line on it is probably a vent for purging air ouf of the cooling system.

Sorry, I do not know any part numbers, but any Daewoo dealer parts department should be able to find you one in a flash.

Some aftermarket parts stores (NAPA, Pep Boys to name a few...) might be able to find you one too, but I`m not 100% sure on this one... Sometimes Daewoo parts are hard to find aftermarket.