GMC 1996 Sierra Owner's Manual page 249

Rocking your vehicle to get it out:
First. turn your steering wheel left and right. That will
clear the area around your front wheels. Then shift back
and forth between REVERSE (R) and a forward gear (or
with a manual transmission, between FIRST ( 1 ) or
SECOND (2) and REVERSE(R)), spinning the wheels
as little as possible. Release the accelerator pedal while
you shift. and press lightly on the accelerator pedal
when the transmission is in gear. If that doesn't get you
out after a few tries. you nlay need to be towed out. Or,
you
can
use your recovery hooks if your vehicle has
them. If you do need.to be towed out, see "Towing Your
Vehicle" i n the Index.
Using the Recovery Hooks