【Application】Perfectly compatible with 2003-2006 Ford pickups and vans with 6.0L powerstroke diesel engines. 【High Performance】Specially designed to connect the part number 5021 diesel engine compression gauge to a glow plug port (after the glow plug has been removed) for performing a compression test. 【Direct Replacement】Comparable to OEM part number 6660 303-757 both in quality and functions. Used with J-6692-B 303-D092 AM-303-D092 J-26999 compression test gauges. .