Chevrolet Avalanche Owner's Manual page 312

And, if you do have a heavy load, you should
spread it out.
CAUTION:
{
In the case of a sudden stop or collision,
things carried in the bed of your truck could
shift forward and come into the passenger
area, injuring you and others. If you put things
in the bed of your truck, you should make sure
they are properly secured.
CAUTION:
{
Do not load your vehicle any heavier than the
Gross Vehicle Weight Rating (GVWR), or either
the maximum front or rear Gross Axle Weight
Rating (GAWR). If you do, parts on your
vehicle can break, and it can change the way
your vehicle handles. These could cause you
to lose control and crash. Also, overloading
can shorten the life of your vehicle.
4-52
Your warranty does not cover parts or components that
fail because of overloading.
The label will help you decide how much cargo and
installed equipment your truck can carry.
Using heavier suspension components to get added
durability might not change your weight ratings. Ask your
dealer to help you load your vehicle the right way.
If you put things inside your vehicle — like suitcases,
tools, packages, or anything else — they 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.