1966 Chevelle Rear Seat

[Chevelle LS6]

Does anyone know if their are different ways that the rear seat back is held in place? Does the 300 fasten in different than a 2 door sport coupe? I need a rear seat as it was missing when I bought my project. I can't see where their would be bolts in bottom of the seat back. Only threads with holes or holes at all in the floor pan are where the seat belts were. Their is a small loop welded to the floor that has a small hole in it. Not sure what that is. To me it seems that seat back just sits on the hooks at the top and the bottom must somehow interlink with it. ? Not sure. I see a lot of seats with the back having a tab to the outside of the back at the bottom that is for bolting to the car body. Are these from different division of the A body or 300 or ?
I would like to see pictures of a seat installed with the bottom out. HELP. I need to purchase a seat and want to be sure to get a correct one.