It is located between the cylinder head and the exhaust manifold; it prevents exhaust gases from escaping.
Cummins specifies the primary use for 10-liter L10 engines; aftermarket catalogs extend the application to the M11, ISM, and QSM families. Final compatibility should be verified using the engine’s serial number.
Cylinder head; can be used as a seat for the intake or exhaust valve, depending on the cylinder head configuration.
Compatible engines: Cummins L10 / LTA10. Some aftermarket catalogs also list the M11, but Cummins officially specifies part number 3418040 primarily for non-certified 10-liter L10 engines. Always verify using the Engine Serial Number (ESN).