383 or 5.7 hemi

That is true, but the VVT is the monkey wrench thrown in the mix. VVT trucks have the throttle body pointing straight up into the hood. I was planning on using my 6.1 manifold, having read somewhere on the web that they fit the VVT motors. That may be the case with VVT car motors (although I have not verified that), but they do not, however, fit the truck motors because of the different accessory layout.