GMC 1998 Savana Van Owner's Manual page 67

Accident statistics show that children are safer if they
are restrained in the rear seat. But they need to use the
safety belts properly.
0
Children who aren't buckled up can be thrown out
in a crash.
0
Children who aren't buckled up can strike other
people who are.
Never do this.
Here two children are wearing the same belt. The
belt can't properly spread the impact forces. In a
crash, the two children can be crushed together
and seriously injured. A belt must be used by
only one person at a time.
1-59