DuraWRX DEF Header for Freightliner/Cummins 13/23 Gal Tanks with SAE Flange Analog Level Sensor by DuraWRX. This header assembles the in-tank interfaces required to monitor DEF level, provide filtration, and route DEF for vehicles using 13- and 23-gallon tanks on Freightliner chassis with Cummins engines. The unit includes an analog level sensor and a factory-style 4-pin Amp electrical connector to send a reliable analog signal to dosing and vehicle control modules. A replaceable in-tank filter screens particulates (70 μm rating on this configuration) ahead of the pump and dosing components to reduce the risk of clogging and premature component failure. The header mounts to the SAE J2587-style tank flange and provides SAE J2044 DEF fittings for suction and return plumbing to simplify installation and minimize modification time. The header s integrated sensor and fittings address two common operational failure modes: inaccurate or intermittent level readings that trigger unnecessary service actions, and contamination-related dosing faults that force roadside repairs or extended downtime. For fleet technicians, the header s plug-and-play electrical interface and OE-style mounting mean faster bench or on-vehicle swaps and reduced diagnostic time. Field-fit notes and TSB guidance are available from the manufacturer for vehicle-specific installation steps. Specifying this header helps maintain consistent DEF level reporting to SCR dosing systems and reduces pump and injector exposure to debris, which lowers the frequency of emissions-system repairs and keeps trucks in service for revenue-generating miles.