I have an 04 F-150 4wd 4.6 and have a squeaking noise coming from the rear only when I start to back up. Replaced rotors and pads front and rear and noise still there, found cracked cup on caliper on left rear which I changed out and noise still there............ Changed E-brake shoes yesterday and noise is still there........ any clues? Thanks for any advice

 

Found it! I put her up on jack stands this morning and had the wife put 'r in gear while I listened for the sound............... It was coming from the seal on the rear end. sprayed a little panther **** on her and she's good to go