Chevrolet 2005 Tahoe Owner's Manual page 64

If your child restraint does not have the LATCH system,
you will be using the lap-shoulder belt to secure the child
restraint in this position. Be sure to follow the instructions
that came with the child restraint. Secure the child in the
child restraint when and as the instructions say.
1. Put the child restraint on the seat.
2. Pick up the latch plate, and run the lap and shoulder
portions of the vehicle's safety belt through or
around the restraint. The child restraint instructions
will show you how.
3. Buckle the belt. Make sure the release button is
positioned so you would be able to unbuckle the
safety belt quickly if you ever had to.
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4. Pull the rest of the shoulder belt all the way out of
the retractor to set the lock.