This DOC is for a Paccar MX engine. The DOC is a direct fit replacement for the OEM system to ensure that installation is as quick and easy as possible. The DOC is newly built, not re manufactured or re-conditioned. DOCs are coated with platinum-group metals (PGMs) platinum or palladium to match the catalytic activity level of the OEM component. This item includes all necessary ports and attachments for sensors and is designed to operate in the exact same capacity as the original OEM part.