* Upper intake gasket: This is a thin, usually rubber or composite seal that sits between the upper intake manifold and the cylinder head. Its job is to prevent air and coolant leaks.
* Plenum: This is the main chamber of the upper intake manifold. It's a large, hollow part that distributes air evenly to each cylinder.
Think of it this way:
* The plenum is like the room where the air hangs out before entering the engine.
* The gasket is like the doorway that seals the room and prevents leaks.
You might need to replace both the upper intake gasket and the plenum if the plenum is damaged or cracked. However, the gasket itself is a separate part.
