GMC SIERRA 1995 Manual page 46

Make sure the release button on the buckle is positioned so you would
be able to unbuckle the safety belt quickly if you ever had to.
, '
--\
The lap part
of
the belt should be worn 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 only if there's a sudden stop or a crash.
A
CAUTION:
You can be seriously hurt if 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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