Pontiac 2004 GTO - Manual (Page 30)

2. Slide the guide under and past the belt. The elastic
cord must be under the belt. Then, place the guide
over the belt, and insert the two edges of the
belt into the slots of the guide.
3. Be sure that the belt is not twisted and it lies flat.
The elastic cord must be under the belt and the
guide on top.
1-24