GMC 1993 Suburban Owner's Manual page 43

Center Passenger Position (Wagon Models Second Seat)
When you sit in the center position of the wagon model second seat, you
have a lap safety belt which has a retractor.
AN145053
1. Pick up the latch plate and, in a single motion, pull the belt across you.
Don't let it get twisted.
2. Push the latch plate into the buckle until it clicks. If the belt stops before
it reaches the buckle, let it go back all the way and start again.
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