GMC 1993 Suburban Owner's Manual page 313

I
Your warranty does
not cover pads or
components that fail because of
overloading.
If you put things inside your vehicle-like suitcases, tools, packages, or
anything else-they will go as fast as the vehicle goes. If you have to stop
or turn quickly, or if there is a crash, they'll keep going.
Things you put inside your vehicle can strike and injure people in a
sudden stop or turn, or in a crash.
Put things in the cargo area of your vehicle. Try
to
spread the
weight evenly.
*
Never stack heavier things, like suitcases, inside the vehicle so
that some of them are above the tops of the seats.
* When you carry something inside the vehicle, secure it
whenever you can.
a
Don't have a seat folded down unless you need to.
If your vehicle comes with the Trailering Package, there is also a load rating
which includes the weight of the vehicle and the trailer it tows. This rating is
called the Gross Combination Weight Rating (GCWR).