FORD 2011 F-550 v.1 - Manual (Page 203)

The tether strap anchors in your vehicle are in the following positions
(shown from top view):
• F-Series Regular Cab
• F-Series SuperCab
• F-Series Crew Cab
Attach the tether strap only to the appropriate tether anchor as shown.
The tether strap may not work properly if attached somewhere other
than the correct tether anchor.
Once the child safety seat has been installed using the safety belt, you
can attach the top tether strap.
Seating and Safety Restraints
203
2011 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)