GMC 2006 Sierra - Manual (Page 109)

Tailgate Removal
The tailgate on your vehicle can be removed to allow for
different loading situations. Although the tailgate can be
removed without assistance, you may want someone to
assist you with the removal to avoid possible damage to
the vehicle.
To remove the tailgate, do the following:
1. Raise the tailgate
slightly and release
both retaining cable
clips. To release the
retaining cable clips,
lift the cable so it points
straight out and push
the cable clip forward.
2. With the tailgate at a
slight upward angle,
pull back on the tailgate
at the right edge and
then move the tailgate
to the right to release
the left edge.
Reverse the above procedure to reinstall. Make sure the
tailgate is secure.
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