GMC 1996 Sierra Owner's Manual page 77

REVERSE (R): Use this gear to back up.
NOTICE:
Shifting to REVERSE (R) while your vehicle is
moving forward could damage your transmission.
Shift to REVERSE (R) only after your vehicle
is stopped.
I
rock your vehicle back and forth to get out of snow.
ice or sand without damaging your transmission, see
"Stuck: In Sand. Mud, Ice or Snow" in the Index.
NEUTRAL (N): In this position, your engine doesn't
connect with the wheels. To restart when you're
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
I
Shifting out of PARK (P) or NEUTRAL (N) while
your engine
is
"racing" (running at high speed) is
dangerous. Unless your foot is firmly on
the
brake pedal, your vehicle could move very
rapidly. You could lose control and hit people or
objects. Don't shift out of PARK
(P)
or
NEUTRAL (N) while your engine is racing.
I
NOTICE:
Damage to your transmission caused by shifting
out of PARK (P) or NEUTRAL
(N)
with the
engine racing isn't covered by your warranty.
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