I think your confused, the inlet manifold has the unique build number. The exhaust manifold is behind the engine and if it still has the heat shield on it looks the same as the rest.
if you have the Miltek minfidold and no heat shield you must check the base of your steering shroud. It is prone to melting! if no heat shield is fitted on the exhaust manifold
19th September 2008: if you have bought a Janspeed manifold please read here clicky me