Where is the PCV valve located?

I have been trying to locate the location of my PCV valve for two years now. Please send a picture of exactly where it is located. I have been told it should be on the valve cover, under the exhaust that comes off the manifold, behind the manifold, and on the oil separator. And it's not in those locations. I'm starting to think either it is a Houdini or there is not one on there at all.