Forewarned is forearmed. When I pulled my engine (1981 MD11c) out 2 months ago I discovered that the head surface passageways on the rear head, that interface with the manifold had a good amount of wear and vanishing metal surface, up to 1/8" inside in some areas. Had to add welding to the head and had it resurfaced with a fine sharpening stone until all was very smooth. I also took this stone and ran it over the exhaust manifold and thermostat block and housing connection so all connection surfaces looked brand new! In addition to the new manifold gaskets I also used (forgot the name) a red colored gasket sealant (in many areas can be used in place of a gasket, like the connection face of the engine and transmission, recommended by the Tranny shop) Also good for filling in little dents and holes on you surface connections.
I anticipate being leak free this season.....
