Chevrolet 1993 S-10 Pickup Owner's Manual page 215

Parking on Hills
You really should not park your vehicle, with a trailer attached, on a hill. If
something goes wrong, your rig could start to move. People can be injured,
and both your vehicle and the trailer can be damaged.
But i f you ever have to park your rig on a hill, here's how to do it:
1.
Apply your regular brakes, but don't shift into P (Park) yet, or into gear
2. Have someone place chocks under the trailer wheels.
3. When the wheel chocks are in place, release the regular brakes until the
chocks absorb the load.
4. Reapply the regular brakes. Then apply your parking brake, and then
shift to P (Park),
or
R (Reverse) for a manual transmission.
5. If you have a four-wheel-drive vehicle with a manual transfer case shift
lever, be sure the transfer case is in a drive gear-not in N (Neutral).
6. Release the regular brakes.
for a manual transmission.
A
It can be dangerous to get out of your vehicle if the shift lever is not
fully in P (Park) with the parking brake firmly set. Your vehicle can
roll.
If you have left the engine running, the vehicle can move suddenly.
You or others could be injured. To be sure your vehicle won't move,
even when you're on fairly level ground, use the steps that follow.
If you have four-wheel drive with a manual transfer case shift lever
and your transfer case is in N (Neutral), your vehicle will be free to
roll, even if your shift lever is in P (Park). So be sure the transfer
case is in a drive gear-not in N (Neutral). If you are parking on a
hill, or if you're pulling a trailer, see also "Parking On Hills" in the
Index.
When You Are Ready to Leave After Parking on a Hill
1. Apply your regular brakes and hold the pedal down while you:
Start your engine.
Shift into a gear; and
Release the parking brake.
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