I'm really feeling lazy at the moment and the only right part I could find without getting out the manuals was on eBay, so I'll get the next-closest thing:
https://www.easternsurplus.net/PartDetails/3310/Rear-Cable-and-Stud
Each rear seat uses a cable assembly like what's in that link, except that the cable is longer and has two studs on it. The end of the cable screws in to the side of the seat back and the locking studs pass through a pair of large holes on the back of the seat back to lock to the fender (you have to slide the seat back behind the seat base correctly to get the holes to line up). If you are in the 2-door configuration, you lay the seat back down so that you have two holes line up with the infamous support bar behind the driver & commander seat and the locking studs will instead insert and lock into that bar. With that seat back in front of you, it should all make sense.
Edit: In hindsight, that IS the correct part that I linked, except you're just missing one stud. The second stud would just be slid onto the cable before installing it to the side of the seat base, that way you can move it around on the cable to get the hole alignment correct depending on which configuration you have the seat back placed in.
