The housing is held together with 3 bolts and splits in two , a steel pipe goes on the other end with an o ring seal . to get at the thermostat you will first have to remove 2 bolts on the steel pipe which holds it in place on the engine doing this gives you more play to sperate the housing . I done this from the top of the engine and getting my hands down back of engine . You could also remove the inlet manifold to get more access but can be done without removing it but less space .