Chevrolet 1998 Express Van Owner's Manual page 13

Removing the Rear Seat
2. Lift the carpedmat flap at the inboard side of the seat
base in the rear.
1. Disconnect the quick release latch plates for the lap
shoulder belts on the bench seat to be removed. To
do this, press the tip of a key into the release hole
of the safety belt buckle while pulling up on the
safety belt.
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