B3.9, B4.5, and B5.9 Industria [...] Cummins® Service Engine Model Product Identification Section E - Engine and System Identification Page E-7 Cummins® Service Engine Model Product Identification General Information The Cummins® Service Engine Model Nomenclature procedure describes how engines are identified within Cummins service organization. This method was introduced for models after and including manufacture year 2007. Electronic engines are identified by the first two letters, either an "IS" for On-Highway automotive or "QS" for Off- Highway industrial market applications.