This is a replacement Ford thermostat housing. In many cases, when changing the thermostat, the housing does not want to re-seat and seal properly. They are made of stamped steel and are not treated very well from the factory against rust. They rust and the seat becomes very uneven. We offered this part for those that wanted to eliminate the chance of leaks when changing your thermostat. From reports back from customers, most would have gladly replaced the housing after seeing what theirs looked like after removal.