1997 GMC Savana Van Owner's Manual - Page 59

Never do this. Here a child issitting in a seat that has a lap-shoulder belt, but the shoulder part is behind the child. If the child wears the belt inthis way, in a crash the child might slide under the belt. The belt's force would then be applied right on the child's abdomen. That could cause serious or fatal injuries. Wherever the child sits, the lap portion of the belt should be worn low and snug the hips, just touching on the child's thighs. This applies belt force to the child's pelvic bones in a crash. 1-51