I have a used 2005 F-150 and am not sure what the situation is vis-a-vis lockers.
Performance in snow w/4WD engaged is bad, bad, bad.... much, much worse than my Suburban in 2WD.... And I am ascribing that to the light rear.
In my Suburban, the front wheels were automagically locked when it was in 4WD but the rear wheels needed an add-on differential locker that needed tb manually engaged (which I did not have)
Same deal with this F-150 ?
If there were a diff locker for the rear, could there be a switch or something on the dashboard that I am not seeing.