GMC 2002 Yukon Denali Owner's Manual page 25

To replace the 50/50 split bench, do the following:
1. While holding the rear of the seat up, slide the front
wheels into the slots on the floor. The front latches
should lock into place. If the latches do not lock, try
tilting the rear of the seat upwards.
3. Push and pull on the seat to make sure it is
locked into place. The seatback cannot be raised
to the upright position unless the seat is secured
to the floor.
1-18
2. Once the latches are
engaged, let the seat
drop into place. Release
the lever labeled 1 and
pull the seatback up
using the assist strap on
the outboard side of the
seat to return it to its
upright position.
Full Bench Seat (Third Row)
If your vehicle has a full bench, the seatback can
be folded and the seat can be tilted or removed from
the vehicle.
Folding the Seatback
CAUTION:
If the seatback isn't locked, it could move
forward in a sudden stop or crash. That could
cause injury to the person sitting there. Always
press rearward on the seatback to be sure it
is locked.