Chevrolet 2009 Suburban Owner's Manual page 78

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:
1-72
If the position you are
using does not have a
headrest or head restraint
and you are using a
single tether, route the
tether over the seatback.
If the position you are
using does not have a
headrest or head restraint
and you are using a
dual tether, route the tether
over the seatback.
If the position you are
using has an adjustable
headrest or head restraint
and you are using a
dual tether, route the tether
around the headrest or
head restraint.