GMC 2004 Yokon Denali Owner's Manual page 68

Yukon XL Denali Third Row Seat
An anchor loop bracket for a top strap is located at the
bottom rear of the seat cushion for each seating
position in the second row, and for the center seating
position in the third row on bench seats.
1-62
Yukon Denali models: A child restraint with a top
strap should only be used in the second row or third row.
Don't use a child restraint with a top strap in the right
front passenger's position, because there's no place to
anchor the top strap.
Do not secure a child restraint with a top strap in the
right front passenger's position or in the third row driver's
side position if a national or local law requires that the
top strap be anchored, or if the instructions that
come with the child restraint say that the top strap must
be anchored. There is no place to anchor the top
strap in these positions.
An anchor loop bracket for a top strap is located at the
bottom rear of the seat cushion for each seating
position in the second row, and in the outboard
passenger position in the third row for 50/50 split seats.