2012 Tacoma seat back help

Hey so I have a 2012 Tacoma and both the driver and passenger seats are missing something that goes on the bottom of the seats on the back. The local dealer gave no help other then a part that doesn't even go to my vehicle. I've attached a picture of the seat. Any help is greatly appreciated

 

I have nothing to offer, other than to say "that's weird". Why would that possibly be missing?

 

I'm assuming the seats are the same on a 15. Since I just pulled mine off and put on leather here are a few pictures for you. There is a 'flap' on the seat top that goes down and attaches to the seat bottom. It has carpet material on the outside, and a hard plastic backing. The 'flap' is sewn to the seat top cover. There is a part number on the hard plastic backing if that helps

 

Did you buy the truck new? If not the last owner probally had seat covers on like wet okols where you have to do something with that flap so you can install the seat backs, first check the seat backs to see if they are folded up inside the backs, if not check to see if the have been cut off cause they are attached to the seat back.

 

^^^^^ This. The seat cover instructions tell you to tuck them up under the seat back for the cover installation. They should have hooks at each corner so you can hook it under the seat to hold it in place.