Ford 2008 F-150 Owner's Manual page 143

will allow the handles to stick up above the lid (with the lid closed).
After closing the lid, simply lift up and inboard away from the pickup
box side to release bin from rail.
To install, reverse the above instructions.
Note: Remove the bins during severe off road driving to avoid damage to
the cargo bins and pickup box.
If any levers are visible above the lid of the bin, the bin is not
securely attached to the rail, and may become detached from the
vehicle if driven in that configuration.
2008 F-150
Owners Guide (post-2002-fmt)
USA
Driver Controls
143