Chevrolet 2008 Silverado 1500 Pickup Owner's Manual page 72

5. Pull the rest of the shoulder belt all the way out of 6. To tighten the belt, push down on the child restraint,
the retractor to set the lock. pull the shoulder portion of the belt to tighten the lap
portion of the belt and feed the shoulder belt back
into the retractor. If you are using a forward-facing
child restraint, you may find it helpful to use your
knee to push down on the child restraint as you
tighten the belt.
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