GMC 2004 Yukon XL Owner's Manual page 68

Securing a Child Restraint in a
Rear Outside Seat Position
If your child restraint is equipped with the LATCH
system see Lower Anchorages and Top Tethers for
Children (LATCH System) on page 1-59. See Top Strap
on page 1-55 if the child restraint has one.
1-62
There is no top strap anchor at the third row driver side
seating position. Do not secure a child seat in this
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.
If your child restraint does not have the LATCH system,
you'll be using the lap-shoulder belt to secure the child
restraint in this position. Be sure to follow the instructions
that came with the child restraint. Secure the child in the
child restraint when and as the instructions say.
1. Put the restraint on the seat.
2. Pick up the latch plate, and run the lap and shoulder
portions of the vehicle's safety belt through or
around the restraint. The child restraint instructions
will show you how.