Just to be clear, do you need number 7 in this diagram?
The parts book calls it out as "Bumper, Rear Seat Back" and lists it KF part number 212133.
Unfortunately, my cars are in storage for the winter so I can't just go out and look at it. I'm sure someone else may be able to clarify what it is or what might be used as a sub. I've never really looked at mine to be honest.
Let us know so hopefully we can all benefit from the discussion.