Chevrolet 2006 Express Van Owner's Manual page 52

There are two top tether anchors in the second row.
To install a child restraint in the left outboard seating
position, use anchor point (A). To install a child restraint
in the right outboard seating position, use anchor
point (B). To install a child restraint in the center seating
position, use either anchor point (A) or (B). Never
install two top tethers using the same top tether anchor.
Second Row — Passenger Van
1-46
There is a top tether anchor for the center seating
positions in the third and fourth rows, if equipped with a
three-passenger bench seat. The anchor is located at
the bottom rear of the seat cushion.
Third or Fourth Row — Three Passenger
Bench Seat