GMC YUKON XL 2004 Owner's Manual page 16

To create a load floor release the panels from the
seatback by pushing forward on the latch. Then fold the
panels back to cover the rear seat footwell area.
1-10
To return the seat to the passenger position on a
extended model do the following:
1. Lift the floor load panels and latch them into the
seatback.
2. Lift the seatback up and push rearward all the way.
3. Lower the seat cushion until it latches into
position.
4. Pull forward on the seatback and up on the seat
cushion to make sure the seat is securely in place.
Make sure that the buckles on the driver's side seatback
are accessible to the outboard and center occupant
and are not under the seat cushions.
On regular models make sure the head restraints are
returned to the upright position.