Direct OEM Replacement – Precision-engineered fuel system kit includes a fuel check valve (3033740) and threaded plug (3033742), directly replacing OEM numbers for Cummins diesel engines.Maintains Stable Fuel Pressure – The 3033740 check valve prevents fuel backflow and ensures consistent fuel supply for reliable engine operation. Compatible with HPI fuel systems on EPA07 15-liter ISX/QSX engines.Seals Threaded Openings Securely – The 3033742 threaded plug features a 3/8-24 thread and includes an O-ring seal (3034412) for leak-proof sealing of ports in the engine block or fuel system during maintenance.Extensive Engine Compatibility – Designed to fit a wide range of Cummins engines, including ISX, QSX 15L, NT855, N14, N14 CELECT, N14 CELECT Plus, G14, G855, and more.Professional Installation Recommended – Direct-fit for engine repair and fuel system maintenance. Professional mechanic installation is recommended. Please verify your engine model before purchasing.