GMC Denali 2004 Owner's Manual page 49

When using a child restraint with a top strap in either
rear outboard position, raise the head restraint and route
the top strap through the fabric loop on the seatback.
Then, attach the top strap to the anchor point at
the center rear seating position.
When using a child restraint with a top strap in the
center rear position, route the top strap through
the fabric loop on the seatback. Then, raise the head
restraint and attach the top strap to the anchor
point located at the closest outboard position.
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