Rear-end squeal/squeak
 

Have a 2003 Ford F150 4x4. Last week when driving it home I started hearing a really loud squeal only when accelerating. Lasted about a day and went away.

I jacked it up and checked rear brakes (only a couple weeks old), bearings etc... all seemed good. It went away for a week or two but now is back. Here's the strange thing. it now only occurs around 10-12 miles an hour or when going around sharp corners.

Driving me insane... Any ideas of things to check are greatly appreciated