Re: changing thermostat
the thermostat housing is where the top hose connects to the radiator typically. it's like an L shaped aluminium tube on my car.
you will have to drain ur radiator, then remove the top hose and thermostat housing. It's like 2 bolts. then the thermostat retainer should be pulled out and the thermostat and it's rubber grommit thing should come out easy peasy.
Then put ur new thermo in, replace the retainer and bolt it back on! Reconnect hoses and bobs ur uncle.
It's worth while to flush out ur cooling system while you've got the hoses off, too.
Car owner by neccesity, Ford owner by choice.