Pontiac Sunbird Owner's Manual page 26

If the belt stops before it reaches the
buckle, tilt the latch plate and keep
pulling until you can buckle it.
If the belt is not long enough, see the
Index under Safety Belt Extender.
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.
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3. To make the lap part tight, pull down
on the buckle end of the belt as you
pull up on the shoulder part.
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.
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