Rear headrests
#21
Did that at times with my YJ's backseat while I was in college renting a room in a house, so I had limited space, worked great.
#22
Someone has done a right up on it here. It looks like you'll need a flathead screwdriver. It definitely DOES NOT pop right off. Kinda weird that it's different between the models. I guess they're trying to accomodate for the way the rear seats fold down in the unlimited. Hope this helps!
https://www.jk-forum.com/forums/jk-write-ups-39/rear-headrest-removal-6069/
https://www.jk-forum.com/forums/jk-write-ups-39/rear-headrest-removal-6069/
#23