GMC 2005 Yukon Owner's Manual page 62

Third Row 50/50 Split Bench Seat
Your vehicle has a top strap anchor for each seating
position in the second row, and for the center seating
position in the third row. The anchors are located at the
bottom rear of the seat cushion.
Do not secure a child restraint with a top strap in the
right front passenger's position or in the third row
outboard seating positions 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.
1-56
Lower Anchorages and Top Tethers
for Children (LATCH System)
Your vehicle has the LATCH system. There are anchors
for the center and right side passenger second row
seating positions for bench seats, and the outboard
passenger positions for bucket seats.
This system, designed to make installation of child
restraints easier, does not use the vehicle's safety belts.
Instead, it uses vehicle anchors and child restraint
attachments to secure the restraints. Some restraints
also use another vehicle anchor to secure a top
tether strap.