Chevrolet 2001 Express Van Owner's Manual page 21

For the remaining rear seats, stow the safety belt
latch plate on the clip at the window trim.
1-8
Replacing the Rear Seats
CAUTION:
A seat that isn't locked into place properly can
move around in a collision or sudden stop. People
in the vehicle could be injured. Be sure to lock
the seat into place properly when installing it.
CAUTION:
A safety belt that is improperly routed, not
properly attached, or twisted won't provide the
protection needed in a crash. The person wearing
the belt could be seriously injured. After
installing the seat, always check to be sure that
the safety belts are properly routed and attached,
and are not twisted.
1. Remove the trim covers from the floor rails and store
for future use.