The Offenhauser intake has a full length water jacket/hournal . With the correct cover plate (from Tom Langdon and a few others), water flows into a fitting on one side of the plate, to the end of the intake manifold, and then to the other side of the manifold, and finally flows out the second hole (hose fitting) in the manifold. The Offy manifold has a "divider" where the water plate mounts - this allows the water to flow from one side to the other.
Clifford's water-heated intake manifolds (they used to also sell non-water-heated manifolds) do not need a water-hose mounting/cover plate; the hose fittings attach directly to the manifold, into the journal/jacket cast into the manifold.
One feature of the Offenhuaser manifold is if you are using the stock exhaust or a dual exhaust manifold that still has the damper/butterfly on one of the manifolds (this might be true for conversions from Kansas Kustoms), you can obtain heat to the multicarb intake from the header that is attached to the intake (no need for water hoses or the water plate).
Tim
