Rear seat belts 65 valiant

I got my new valiant home, and I am in the process of getting her All cleaned up and ready to enjoy.

One of the safety upgrades that going to need to do to is to install rear seat belts... I have them in the front, but not back, and before I can take my daughter for a cruise I need to fix that!

I understand, from what I've read, that the car is likely already ser up to just bolt them in place... Does anyone know exactly where the mounts are?

Also- how does the rear seat come out? One side seems to "pop" out at the top when I pull on it, like its on a spring clip or something ?

Thanks