Starter noise??
 

I have an 06 XLT 4x4 5.4 and sometimes once a week or less I get a loud grinding sound like when your truck is running and you stupidly crank it and you get that god auffle sound!! I'm getting it with the truck off! After it does it I try again and she starts up?? Any ideas??

Bad bendix or bad spot on flywheel.

Check and make sure that the starter is tight. When my 04 was doing that it was the bolts were all loose and stripped out. I put a new starter in and replaced the bolts and everything has been fine since.

The boss's did the same thing last year and when I removed the starter it had chewed up the flywheel already. Also the replacement starter from advance auto parts bendix would not engage far enough to meet the flywheel. So I had to take the new gear and put it on the old starter. Can send a pic of the old flywheel if you need me to. If you remove it the top inside bolt in the starter is a real pain in the butt. New Starter and flywheel is the cure.