Rear end started roaring at 15000 miles. Ford worked on rear end 5 times and each time the whine would go away. It would then come back after a few thousand miles. It has 180,000 miles on it now and whine is really very loud I would love to know a permanent fix. I've replaced only the water pump and alternator so I would like to get rid of the whine. My wife has had 2010,2011, and 2013 4 x4 Explorers with no problems at all on any of them. She put 25 to 35,000 miles on each and they were perfect. Maybe she has been lucky.