GMC Yukon Owner's Manual page 107

Some child restraints with top tethers are designed for
use with or without the top tether being attached. Others
require the top tether always to be attached. In Canada,
the law requires that forward-facing child restraints have
a top tether, and that the tether be attached. Be sure to
read and follow the instructions for your child restraint.
If the child restraint does not have a top tether, one can
be obtained, in kit form, for many child restraints. Ask
the child restraint manufacturer whether or not a kit is
available.
Lower Anchor and Top Tether Anchor
Locations
Second Row 60/40
(Lower Anchor):
Seating positions with two
lower anchors.
(Top Tether Anchor):
Seating positions with top
tether anchors.
Second Row Bucket
Third Row Three
Passenger
(Lower Anchor):
Seating positions with two
lower anchors.
(Top Tether Anchor):
Seating positions with top
tether anchors.
(Top Tether Anchor):
Seating positions with top
tether anchors. There is
one top tether anchor that
can be used for either the
third row center or driver
side seating position but
not both at the same time.
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