FORD 2010 F-550 v.1 - Manual (Page 173)

WARNING: Each seating position in your vehicle has a specific
safety belt assembly which is made up of one buckle and one
tongue that are designed to be used as a pair. 1) Use the shoulder belt
on the outside shoulder only. Never wear the shoulder belt under the
arm. 2) Never swing the safety belt around your neck over the inside
shoulder. 3) Never use a single belt for more than one person.
WARNING: When possible, all children 12 years old and under
should be properly restrained in a rear seating position.
WARNING: Safety belts and seats can become hot in a vehicle
that has been closed up in sunny weather; they could burn a
small child. Check seat covers and buckles before you place a child
anywhere near them.
WARNING: Front and rear seat occupants, including pregnant
women, should wear safety belts for optimum protection in an
accident.
Combination lap and shoulder belts
1. Insert the belt tongue into the
proper buckle (the buckle closest to
the direction the tongue is coming
from) until you hear a snap and feel
it latch. Make sure the tongue is
securely fastened in the buckle.
Seating and Safety Restraints
173
2010 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)