GMC 2007 Yukon XL Owner's Manual page 79

For vehicles with a three passenger third row seat,
there is one top tether anchor located at the
bottom rear of the seat cushion that can be used
for the third row center or driver side seating
positions. Never install two top tethers using the
same top tether anchor.
Do not secure a child restraint in the right front
passenger position or the third row passenger side
seating position if your vehicle has a third row seat,
if a national or local law requires that the top tether
be attached, or if the instructions that come with the
child restraint say that the top tether must be
attached. There is no place to attach the top tether
in these positions.
Accident statistics show that children are safer if
they are restrained in the rear rather than the front
seat. See Where to Put the Restraint on page 72
for additional information.
79