05 Expedition EB 4x4 109,000 miles Alway drive in 2WD mode We are second owner and have owned the car since 7/11 when we purchased it with 91K miles on it. Popping and clicking started around 96K miles. Noise is coming from the drivers side it seems. First started after allowing it to rest awhile and only when backing up out of garage on a level surface with wheels slightly turned. Just barely got the car rolling and a loud pop/click would sound. Over the last 12K miles the noise has gotten worse and it pops and clicks backing up, turning the wheels and accelerating forward. Same noise now over small bumps at lower speeds driving straight or turning. Basically hear it all the time except at high speeds. Noise is usually one loud pop followed by lots of smaller clicks kind of like bad CV joint(s). Self diagnosis: Checked the vacuum lines heading to the front wheels which powers the 4x4. They are fine. CV boots are fine and rotate with wheels turned and make no noticable noise. No overly large amount of play in wheel when wiggled up/down. Left/right seems to have a little play but it seems normal - like steering assembly play. Tested A4WD, 4Hi and 4Lo and issue is present under all settings (key on, motor off). 4Lo works as it should. Suspect 4Hi does too. Watched and listened for noise as wife backed vehicle up (vehicle is in 2H). Noticed: - CV joints did not rotate (logic says this is good) - Loud pop noise (unidentifiable location - somewhere between front center and drivers side wheel) - CV joints and drive shafts started spinning while backing up within first 5 feet of moving the vehicle and continued to remain on backing down the driveway and pulling back up. (Seems like hubs should be unlocked and wheels free spinning in 2H) - Usual popping and clicking continued while pulling up driveway and backing back down repeatedly. Jacked up front end and manually rotated tires while in 2WD mode. Hubs remained locked unless key is on and then they unlock. Pop noise almost sounds like something is loose like a suspension component. Click noise sounds like it's in the 4x4. What is the issue(s)? Can anyone tell me how to isolate them?