The SIDI high-pressure fuel pump mounts upwards towards the inside of the head, and must be installed with the camshaft drive lobe on its base circle to prevent damage to the fuel pump. The fuel pump MUST be drawn in evenly in less-than-full-turn increments. The fuel pump rod can be damaged if the pump is drawn into position. GM-48896 fits into the fuel pump mounting bore in the head, providing a positive indication that the camshaft lobe is on the base circle. If the camshaft lobe is not positioned correctly, the technician will know from GM-48896 that the engine must be turned until the camshaft lobe is positioned correctly.