if you look hard enough on the net you can find these for about $40....now i come from the turbo dodge camp and a mopar guy at heart..i love my Coronets and have messed with some very potent later 2.2 turbo cars anyway....this little thing is also known as a G valve as in "Grainger Valve" ...not sure but who knows Gus Mahon likely invented it.....anyway here's a link that you might find interesting. boostcontrol
send me a pm and i'll try to get you some more info. thnx.