AccurateDiesel 6.0L Powerstroke Billet Aluminum 3 Piece Cap Set - Oil Filter AND Upper / Lower Fuel Filter Caps with Pressure Ports These billet aluminum caps will be the last you will ever need - no more plastic caps that round off easily! Anodized silver to dress up your engine compartment; Proudly made in the USA For all 2003 - 2007 6.0L Powerstroke Diesel (Trucks only) Secondary Fuel Cap (located on top of the engine) includes 1/8th NPT pressure test port - the easy way to measure fuel pressure! Lower Fuel Cap Test Port can be used to check suction side of fuel pump; Oil Cap also includs port for measuring oil pressure, temperature, or connecting a bypass oil filter system.