Name this part

[tomgarrett]

Below is a picture of the part I broke off my Mk2 VTR when changing the clutch.
Does anyone know what it's called and where I can buy a replacement?

http://s2.postimg.org/6xqz7g79l/p4pb6414403.jpg

[tomgarrett]

Is it the radiator flange/thermostat housing?

[CarlStinson]

Its your thermostat, only about £8 for a new one two bolts hold it on make sure it comes with a new gasket
eurocarparts sell them I just replaced mine

[Vspeck23]

Thermostat house £8.50 with a new thermostat from euro car parts