GMC Yukon XL Denali 2005 Owner's Manual page 17

Yukon XL Denali: On the passenger side of
Yukon XL Denali models, the lever at the base of the
seat must be pulled up to release the seatback. Pull
the seatback forward and fold it down until it is flat.
If the seatback cannot fold flat because it interferes with
the cushion, try moving the front seat forward and/or
bringing the front seatback more upright.
On Yukon XL Denali models only, once the seatbacks
are folded down, the rear seat footwell area will be
exposed and will have to be covered by the load floor
panel(s). To create a load floor, do the following:
1. Release the panels from the seatbacks by pushing
forward on the latches.
2. Then fold the panels back to cover the rear seat
footwell area.
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