Assemble a custom fuel system or an auxiliary cooler in your 4BT Cummins with the Adapter Fittings available at XDP. XDP carries a wide variety of different thread pitches and fitting sizes from the top manufacturers. Find the different styles of connectors you need to properly set up various custom systems in your vehicle. Whether you’re working on the oil system or fuel system in your Cummins, XDP is sure to have what you’re looking for. These fittings are constructed with durable materials to withstand fuel, oil, or transmission fluid to provide a long service life. XDP has the Universal Components your 3.9L 4BT Cummins needs.