This is the exhaust back pressure sensor for the 7.3L Powerstroke engine. It is used in the 1997-2003 F250-F550, 2000-2002 F650/F750, 1995-2004 E Vans, and in the 2000-2003 Excursions.
Feel free to contact our parts department at 800-891-8038 with any questions.