Chevrolet 1979 Light Duty Truck Owner's Manual page 24

it through the slot. Pull the knob firmly upward to seat it at the
narrow end of the keyhole. Then fasten the lap belt. Do this in
reverse when taking off the shoulder belt and putting it away.
•
The detachable shoulder belts can be made shorter and longer in
the same way as center seat lap belts.
•
The detacha ble shoulder belt should have enough slack to put
a fist's width between your chest and the belt. This can be checked
by putting a clenched fist between the belt and your chest. (Place
thumb side of fist against chest with back of hand up.)
CAUTION:
Use the least amount of belt slack to minimize belt
pressure. Too much belt slack could reduce the amount of protection
because the belt may not be able to properly restrain you in an accident.
Do not wear the shoulder belt under your outer arm or otherwise out
of position. Such use could increase the chance and/or the severity of
injury in an accident.
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