Strong Compatibility -- Fuel System Coupler Fitting Tool Fit for Detroit Diesel S60, Cummins, Caterpillar, MBE900, MBE4000 Engines. Fast and Secure Connection -- Fuel system coupler fitting is connected to the hose of ONI581T and assists with fuel system priming by connecting to the fuel system through a “compu-check” quick connect fitting, for Detroit Diesel S60, MBE900, MBE4000, DD13, and DD15 Fuel System Priming Pump.