The below engine parts Cummins muffler are for the 4BT3.9/6BT5.9/6CT8.3/6LT8.9/ISDe/ISLe/ISZ/M11/NT855/ KT19/KT38/KT50/ISF2.8/ISF3.8/ISM11/QSM11 series. Cummins engine. Part Name Part No. Part Name Part No. Cummins Muffler C4988423 Noise Isolator 3935449 KG5 Muffler 3055655-20 Muffler Bracket 3971043 Exhaust Muffler 4914725-20 Cummins Muffler 3971045 Cummins Muffler 3055653-20 Cummins Muffler 4988336 Muffler Assy 3165746-20 Cummins …