THe Marnal and Alabama castings are alternates, but I don't think it's the head. The clearwater comes without the cam plug installed, because it's in the head gasket set, a plastic cup about a half inch deep. It's in the pressure oil path, and I bet it was never installed, or installed dry. It WON'T come out unless the rear cam bearing cap was not torqued down, and in that case, the oil will leak like crazy at the joint between the halves of the rear cam bearing cap, because the oil gallery passes thru the cap.

I see an install error here. And I'm with WWFF here, my son or not. Pilots are not all that bright. Know how you tell a pilot in the shower? Big watch and tiny hootus. THere was a study done just prior to ww2 that showed that the best pilot was a high class moron, who lacked the intelligence to become bored while flying....