Pontiac 2003 Montana Owner's Manual page 50

Lap Belt
If your vehicle has bucket seats, someone can sit in the
center position bucket seat.
1-44
When you sit in the center position bucket seat, you
have a lap safety belt which has a retractor.
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. Pull up on the
latch plate to make sure it is secure.
3. Feed the lap belt into the retractor to tighten it.