GMC Express 2011 Owner's Manual page 105

2.3. Route and tighten the
top tether according to your
child restraint instructions
and the following
instructions:
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.
Seats and Restraints
If the position you are using
has an integrated headrest
or head restraint and you
are using a dual tether,
route the tether around the
headrest or head restraint.
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