I rarely drive the wifes vehicle (08 expedition 66K mi) but I took it for a ride yesterday and it sounded like a wheel bearing was growling but now I'm thinking that the hubs are locked in. The switch is set on 2H but her gas milage has dropped to 10.3 mpg..I heard that there is a vacuum line that operates the hubs where should I look??

 

You're talking about the IWE (integrated wheel ends).

This is the best place to start:
https://www.ford-trucks.com/forums/8...then-some.html

-Chuck