Ford Repair: camshaft position sensor, haynes book, camshaft position sensor

Question
Tony,
1995 explorer limited 4.0. 107,000 miles.  Check engine light is on and off (more on) truck runs OK. Need to get smog test. Repair shop said I need a camshaft position sensor with the synchonizer. repair cost is over $700. have been checking online. appears the sensor itself can be changed and is fairly inexpensive and easy to remove. Is there a reason to change the entire unit?
I am unable to locate the CMP. Haynes book shows different engine.  descriptions online seem to vary.
Thanks for you time.
Steve

Answer
Hello Steve, What happens is the bushing in the scynro gets worn and causes the shaft to turn off center, it in turn hits on the sensor causing it to fail. It will make a difference if it is a 4.0L ohv or a 4.0L sohc. Some are located at the back of the engine not easily accessable. Hope this helps Thanks Tony