GMC 1998 Savana Van Owner's Manual page 11

Power Seat (Option)
If your vehicle has a power seat on the driver's or
passenger's side, you can adjust it with this switch at the
front center cushion of the seat.
You can use these switches to move the seat to where
you want
it.
To raise the seat, move the center knob up.
To lower the seat, move the center knob down. To move
the seat forward, move the center knob toward the right.
To move the seat rearward, move the center knob toward
the left.
You can raise and lower the front and rear of the seat. To
raise the front of the seat, move the right lever up. To
lower it, move the right lever down. To raise the rear of
the seat, move the left lever up. To lower it, move the
left lever down.
Reclining Seatbacks
To adjust the seatback, lift the front of this lever, which
is located at the inner edge of the seat cushion.
Move the seatback with your body and release the lever
to lock the seatback where you want it. Lean forward
and pull up on the front of the lever and the seatback
will go to an upright position.