Cadillac 2002 DeVille Owner's Manual page 56

Once you have the top strap anchored, you'll be ready to
secure the child restraint itself. Tighten the top strap
when and as the child restraint manufacturer's
instructions say.
Your vehicle has top strap anchors already installed for
the rear seating positions. You'll find them behind the
rear seat on the filler panel.
In order to get to a bracket, you'll have to open the
trim cover.
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Lower Anchorages and Top Tethers for
Children (LATCH System)
Your vehicle has the LATCH system. You'll find
anchors (A) in all three rear seating positions.
To assist you in locating the lower anchors for this child
restraint system, each seating position with the LATCH
system will have the LATCH system symbol on the
seatback directly above the anchors.