Probably lots of different opinions on these things, I say water pumps were painted gray. The fan was black. I believe the manifolds were also gray originally, but the exhaust manifold heat would take the paint off quickly, so most people seem to paint the intake manifold gray and the exhaust manifold cast iron gray, using high temperature paint. Valve covers were gray also. I cannot explain the black remark, lots of things change over the years. That gray paint originally used on the engines, IMHO, was poor paint, and came off easily, probably got repainted a long time ago? Bob Adler is pretty much an expert on these old trucks, he has a good supply, and will give you his opinion. Unfortunately, I do not believe he is a member of this forum, but can be reached at: [email protected]