I'm looking to pick up a set of these heads from a local junk yard and Im wondering how many different types there are and what vehicles I can find them on? I've heard of GT40's, GT40P's, GT40x's... What the the differences??
In iron heads you have GT40s and GT40ps. Main differences are valve sizing and spark plug location, the reason why P heads usually need a header that is designed for the revised plug location
In aluminum you have GT40X, Y and Zs. Not sure what the major differences are between them.
I found a set of GT-40 (non-P) at my local breakers. The non-P GT-40 has the EGR system but not the thermactor (therm is there but not drilled for access from the outside like the e7 heads). You will also need the GT-40's milled to match the OEM combustion chamber size or you will lose compression.