Buick RIVIERA 1993 Manual page 51

Securing a Child Restraint in the Center
Rear Seat Position
1. Make the belt as long as possible by tilting the latch
plate and pulling it along the belt.
When you secure a child restraint in a center seating
position, you'll be using the lap belt.
See the earlier section about the top strap if the child
restraint has one.
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