its mounted to the bottom of the manifold. there is a plate with a gasket, and due to design flaws they leak oil into the manifold causing fouled plugs, plugged up cats, fould 02 sensors, poor performance and poor MPGS. do a search you'll find TONS of info on it. and its not to hard to do if you know vehicles....good time to do dist. cap/rotor plugs, and wires, since you have to take out the manifold.

and from xperiance get the Hughes plenum reienforcment so you dont have to worry about it again.