Fleece Performance 04.5-10 GM Duramax SureFlo Performance Sending UnitPROBLEM: If you are running an aftermarket pump that is mounted external of the fuel tank, you will need to install a draw straw or drill your fuel tank to accommodate a sump. Each of these has some pretty significant drawbacks including the 1 4 tank issues that result in cavitation of the pump when you draw air into the fuel system. SOLUTION: SureFlo is designed to work with externally mounted aftermarket lift pumps and fits directly into your stock