Feature 【Application】The compression test adapter is designed for Ford 6.0L Diesel Engines. Suitable for 2003-2006 Ford pickups and vans with 6.0-liter diesel engines. 【Compatibility】The adapter compatible with OTC No. 5021 Diesel Engine Pressure Gauge. 【Function】With the glow plug removed, the compression test adapter can be used to connect the #5021 gauge to a glow plug port for compression testing. .