In the past 6 weeks I have replaced the starter 4 times. The 1st one(original and each one after) made a loud screetching noise as if the starter gear was just touching the ring gear. I checked the ring gear and no teeth are missing. Any suggestions?

 

Chevrolet starters used to have to be shimmed in order to stop this problem. I have never heard of a ford starter needing this fix but I suppose it could be necessary. The shim is a thin piece of steel with a slotted hole and a regular hole in position if the starter mounting bolts. loosen one bolt and remove the other, put the shim in place and put it all back together. If you are getting the right starter for your truck and it is not some other problem then I would just shim it