Output Shaft Speed Sensor
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
See TURBINE SHAFT SPEED SENSOR & OUTPUT SHAFT SPEED SENSOR under REMOVAL & INSTALLATION in SERVICING - BLACKWOOD, ECONOLINE, EXCURSION, EXPEDITION, "F" SERIES PICKUP & NAVIGATOR article in AUTOMATIC TRANSMISSIONS.