Chevrolet 2003 Astro Owner's Manual page 58

Bench Seats: An anchor bracket is located at the rear
of the seat cushion near the top rear of the seat leg
for each outboard seating position of the second row.
For the third row, an anchor bracket is located at
the rear of the seat cushion near the top rear of the
seat leg for the right outboard seating position.
If you have adjustable head restraints, raise the head
restraint and route the top strap under it.
Passenger Van Bench Seat (Second row)
The third row has one anchor for the passenger side
outboard position only.
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