FORD 2010 F-550 v.1 - Manual (Page 210)

These straps may be secured below the back of the seat with rubber
bands. To access, reach below the back of the seat and pull tether loop
out of the rubber band securing it.
Many tether straps cannot be tightened if the tether strap is hooked to
the loop directly behind the child seat. To provide a tight tether strap:
1. Route the tether strap through
the loop directly behind the child
seat.
2. Attach the strap hook onto the
loop behind an adjacent seating
position.
3. Install the child safety seat tightly
using the vehicle belts. Follow the
instructions in this chapter.
4. Tighten the tether strap
according to the child seat
manufacturer’s instructions.
A single loop can be used to route and anchor more than one child seat.
For example, the center loop can be used as a routing loop for a child
safety seat in the center rear seat and as an anchoring loop for child
seats installed in the outboard rear seats.
Seating and Safety Restraints
210
2010 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)