GMC 1993 Suburban Owner's Manual page 36

If the belt isn't long enough, see "Safety Belt Extender'' at the end of this
section.
Make sure the release button on the buckle faces upward or outward so you
would be able to unbuckle it quickly if you ever had to.
The lap part of the belt should be low and snug on the hips, just touching
the thighs. In a crash, this applies force to the strong pelvic bones. And
you'd be less likely
to slide under the lap belt. If you slid under it, the belt
would apply force at your abdomen. This could cause serious or even fatal
injuries. The shoulder belt should go over the shoulder and across the chest.
These parts of the body are best able to take belt restraining forces.
The safety belt locks if there's
a
sudden stop or a crash.
8: What's wrong with this?
AM120015
A: The shoulder belt is too loose. It won't give nearly as much protection this
way.
You can be seriously hurt i f your shoulder belt is too loose. In a
crash you would move forward too much, which could increase injury.
The shoulder belt should
fit
against
your
body.
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