Chevrolet S10 Pickup 2003 Owner's Manual page 48

In Canada, the law requires that forward-facing child
restraints have a top strap, and that the strap be
anchored. In the United States, some child restraints
also have a top strap. If your child restraint has a
top strap, it should be anchored.
1-42
Anchor the top strap to one of the following anchor
points. Be sure to use an anchor point located on the
same side of the vehicle as the seating position
where the child restraint will be placed. If you have an
adjustable head restraint, route the top strap under it.
When using a top strap-equipped child restraint in a rear
outboard seating position of a crew cab model, route
the top strap over the top of the seatback. Then, attach
it to the anchor point for that seating position.
Once you have the top strap anchored, you'll be ready
to secure the child restraint itself. Tighten the top
strap when and as the child restraint manufacturer's
instructions say.