GMC 1996 Sierra Owner's Manual page 47

Top Strap
If your child restraint has a top strap, it should be
anchored. If you need to have an anchor installed, you
can ask your GM dealer to put it in for you. If you want
to install an anchor yourself, your dealer can tell you
how to do it.
Securing a Child Restraint in a Rear
Outside Seat Position (Extended Cab)
If you nave a Crew Cab, see "Securing a Child Restraint.
in a Rear Outside Seat Position (Crew Cab)" later in
this section.
You'll be using the lap-shoulder belt. See the earlier part
about the top strap if the child restraint has one.
1. Put the restraint on the seat. Follow the instructions
for the child restraint.
2. Secure the child in the child resbaint as the
instructions say.
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