(copied from a rebuild posting) Obtain a new 5/8″ deep steel expansion plug Sealed Power 3813052 or similar. Note that the Mopar Performance high-pressure spring kit P3690944 used to include a new plug but no longer does even if the online image shows a plug. The above 5/8 plug is not as deep as the OEM, which is not an issue, and it is slightly thicker gauge than the OEM plug. I measured the original plug and high-pressure spring assembly and the replacement plug and spring assembly and found that the replacement plug will compress the spring .005″ more than the OEM plug, thus increasing the pressure very slightly but likely unnoticeably. Using a bench grinder or file, bevel the open end of the expansion plug to ease installation.