GMC 1998 Safari Owner's Manual page 22

Bench Seats
If you have bench seats in your vehicle, each seat can
carry up to three passengers. They can also be removed
to increase storage space.
The center bench (if not equipped with a built-in child
restraint) and rear bench seats can be adjusted forward
or rearward by the lever at the front of the seat.
Move the seat adjustment
lever at the front of the seat
toward the passenger's side
to unlock it. Slide the seat
to where you want it. Then
release the lever and try
to
move the seat with your
body,
to
make sure the seat
is locked into place.
The non-touring center bench seat has a pivoting
right armrest. The left armrest can also be used as a
storage compartment.
The optional touring bench seats come with moveable
armrests, individual reclining seatbacks, adjustable
headrests and a fold-down center armrest console.
To adjust your seatback, pull up on the lever on the
lower outside of the seat.
The center bench seatbacks will recline further back
than the rear bench seatbacks.