GMC Yukon 2007 Owner's Manual page 84

2. If the child restraint manufacturer recommends
that the top tether be attached, attach and
tighten the top tether to the top tether anchor,
if the vehicle has one. Refer to the child
restraint instructions and the following steps:
2.1. Find the top tether anchor.
2.2. Route, attach and tighten the top tether
according to your child restraint
instructions and the following
instructions:
84
If the position you are
using does not have a
head rest/restraint
and you are using
a single tether,
route the tether over
the seatback.
If the position you are
using does not have a
head rest/restraint
and you are using a
dual tether, route
the tether over the
seatback.
If the position you are
using has an adjustable
head rest/restraint
and you are using a
dual tether, route
the tether around the
head rest/restraint.