FORD 2012 F-550 v.3 - Manual (Page 210)

The tether anchors in your vehicle may be straps on the seatback or an
anchor bracket mounted to the body shell on the back panel.
The SuperCab rear seat has three straps behind the top of the seat back
that function as both routing loops for the tether straps and anchor
loops.
The tether strap anchors in your vehicle are in the following positions
(shown from top view):
• F-Series Regular Cab
• F-Series SuperCab
Seating and Safety Restraints
210
2012 F-250/350/450/550 (f23)
Owners Guide, 3rd Printing
USA (fus)