GMC Sierra 2005 Owner's Manual page 52

A. Lower Anchorage
B. Lower Anchorage
In order to use the LATCH system in your vehicle, you
need a child restraint designed for that system.
To assist you in locating the lower anchors for this
child restraint system, each seating position with the
LATCH system has visible metal anchors in the
seat where the seatback meets the seat cushion.
1-46
CAUTION:
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If a LATCH-type child restraint is not attached
to its anchorage points, the restraint will not
be able to protect the child correctly. In a
crash, the child could be seriously injured
or killed. Make sure that a LATCH-type child
restraint is properly installed using the
anchorage points, or use the vehicle's safety
belts to secure the restraint, following the
instructions that came with that restraint,
and also the instructions in this manual.