GMC 2010 Sierra Owner's Manual page 99

2. If the child restraint manufacturer recommends that
the top tether be attached, attach and tighten the
top tether to the top tether anchor (loop), if your
vehicle has one. Refer to the child restraint
instructions and the following steps:
Example Rear Driver's Side Position
Example Rear Driver's Side Position
2. 1. When using a child restraint with a top tether
in the rear driver side position:
A. Raise the headrest or head restraint.
B. Route the top tether (B) between the
headrest or head restraint posts, through
the loop (A), behind the inboard headrest
or head restraint post, and under the
center shoulder belt (C).
C. Attach the top tether (B) to the top tether
anchor (loop) (D) at the center rear
seating position.
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