Fleetguard's WF2127 coolant filter replaces Cummins 3680434. The WF2127 is a non-chemical water filter used on ISX Engines. For use with OAT Technology and doesn't require any DCA(Coolant Additives). Cummins Filtration Fleetguard is the OE manufacturer of filtration for Cummins engines. One of the most trusted names in heavy duty diesel and commercial vehicle filtration.