3.7 Dodge PCV system?

Both locations were used at one time or another. You either have the large hard line from the PCV at the rear of left cylinder head going to the manifold, or the smaller line from oil filter housing mounted PCV. The EGR, if equipped is at the rear of the engine on the left side. The metal tube from the intake upper plenum connects to it. If the engine installed was not equipped with it (some do not have them), you will have that fault code present all the time.