Hummer 2006 H3 Owner's Manual page 52

5. If the child restraint is forward-facing, attach and
tighten the top tether to the top tether anchor.
Refer to the child restraint instructions and
the following steps:
5.1. Find the top tether anchor.
5.2. Route and tighten the top tether according
to your child restraint instructions and the
following instructions:
1-46
If the position you are
using does not have a
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
head restraint and you
are using a dual tether,
route the tether over
the seatback.
6. Push and pull the child restraint in different
directions to be sure it is secure.
If the position you are
using has a fixed head
restraint and you are
using a single tether, route
the tether over the head
restraint.
If the position you are
using has a fixed head
restraint and you are
using a dual tether, route
the tether around the
head restraint.