How many types of GT40 heads are there?

[Chietala]

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??

Thanks!

 

[RYC CUKR]

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.

 

[FullAuto]

All you're going to find in a junkyard is GT40 and GT40P heads. Look in late model 5.0 Explorers.

 

[DucatiRdr]

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.