[COMPATIBILITY] --- Catalytic converters compatible with 2004-2006 F150 5.4L 4WD, 2006-2008 Mark LT 5.4L 4WD. Reference Number: 53569, 645217, 30494, 50553, 645218, 30495.These free-flow catalytic converters have bolt-on connections and flange to flange design for effortless installation. [HIGH FLOW PERFORMANCE ] --- Our catalytic convertor are built to meet OEM specifications. They also feature a high flow design to increase conversion efficiency and vehicle power without sacrificing flow rate. [COMPLIANCE WITH EPA] --- The direct-fit catalytic converters are compliant with EPA Standards. Thus, they can be used in most states except California, Maine & New York, not legal for use on vehicles required to meet CA standards. [STAINLESS STEEL OUT SHELL] --- The high flow catalytic converters with heavy-duty stainless steel construction feature maximum durability. Firmly welded connections can withstand high temper and pressures for longer service life. [FLANGE TO FLANGE DESIGN] --- These free-flow catalytic converters have bolt-on connections and flange to flange design for effortless installation. They're also complete with full accessories as gaskets and hardware, facilitating your replacement.