Chevrolet 2006 Silverado 1500 Pickup Owner's Manual page 54

Extended Cab
For extended cab models, the top tether anchors are
located near the top of the seatback for each rear
seating position. In addition to the top tether anchors,
each seating position has a fabric loop at the top of the
seatback that you will use to route the top tether
through. Be sure to use an anchor located on the same
side of the vehicle as the seating position where the
child restraint will be placed.
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Crew Cab
For crew cab models, there are covered top tether
anchors for each seating position located on the back
panel of your vehicle, behind the rear seat. Remove the
trim covers to access the anchors.
Do not secure a child restraint in the front passenger's
position if your vehicle has rear seats, if a national
or local law requires that the top tether be attached, or if
the instructions that come with the child restraint say
that the top tether must be attached. There is no place
to attach the top tether in this position.