fuel filter able to spin on. The DP-1000 filter adapter. http://www.abcprecision.com/fuel-filter-adapter-information.html

This insignificant part, really handy though, allows for spin on filters to be used where a CAV filter head exists. Someone had installed it incorrectly and due to all the pounding we took it eventually knocked the nut off the bolt, never would have known that as the bolt goes into the filter, not visible but once that is loose it allows air into the filter/fuel line.