There is noting under the rear seats I know because I took mine out.
I took out the bottom cushion its only 2 bolts that way I could lay the cargo floor flat then if you remove the head rest on the rear seat when the seats are folded down the front seat has more rearward travel.
My LT had it, I would bet if you just bought the tray it would work.
I would get down under the front seat and look for the rails the tray runs in if you see them then all you need to order is the tray at a Chevrolet Parts Counter at the dealer.
If you know someone that does body or mechanical work, if they buy GM parts you can get a discount using their account.