GMC 1996 Sonoma Owner's Manual page 11

Manual Lumbar Support (Option)
If you have this feature,
there will be a knob on the
outside of the driver and
passenger bucket seats.
Turn
the knob counterclockwise to increase lumbar
support and clockwise to decrease lumbar support.
Reclining Seatbacks (Bucket Seats
or 60/40 Bench)
To adjust the front seatback,
lift the 1eve.r on the outer
side of the seat.
Release the lever to lock the seatback where you
want it. Pull up on the lever and the seat will
go
to
an upright position.
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