GMC Sierra Denali Classic 2007 Owner's Manual page 276

Stalling on an Incline
If your vehicle stalls when you are crossing an
incline, be sure you, and any passengers, get out
on the uphill side, even if the door there is
harder to open. If you get out on the downhill side
and the vehicle starts to roll over, you will be
right in its path.
If you have to walk down the slope, stay out of the
path the vehicle will take if it does roll over.
276
CAUTION:
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Getting out on the downhill (low) side of a
vehicle stopped across an incline is
dangerous. If the vehicle rolls over, you
could be crushed or killed. Always get out
on the uphill (high) side of the vehicle and
stay well clear of the rollover path.