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You don't seem to be getting much help with your integrate head issue. I have done a head swap OEM to OEM on my '79 C10 with the integrated head. There is no oil exchange that I saw between the intke and exhaust manifolds. As far as a diagram, I have found none. However, if you intend to pull the head, buy the gasket set and look at it. You can get a good idea how it all goes together from the gaskets. Your concerns regarding the bolts that secure the exhaust manifold to the intake are not unfounded. I would suggest that you pull the entire assembly as one unit, head and exhaust. Then you can work the exhaust manifold removal on the bench where you can better manipulate getting penetrating oil into the threads and carefully removing the bolts. Take your time. If you have a head exchange dealer ask him if you can look at an integrated head like yours.
Regards,
Ken
