Oldsmobile 2000 Silhouette Owner's Manual page 88

A child restraint with a top strap should only be used in
the second or third row. Don't use a child restraint with
a top strap in the right front passenger's position or in
the center position of a third row seat, because there's no
place to anchor the top strap.
An anchor bar for a top strap is located at the rear of the
seat cushion for each second and third row outboard
seating position, and for the center position of the
second row.
Second Row
1-76
Third Row
Anchor the top strap to this bar. Once you have the top
strap anchored, you'll be ready to secure the child
restraint itself.