70 340 4spd Bench Seat Question

Hello, this is only the second A-body I have owned. I bought as an almost done project.

The previous owner reupholstered the seats but did not completely reassemble them. The front bench is missing the covers on the end and there is nothing holding the seat back on the bar where it pivots. I have seen seats before where there is a hole in the pivot bar, you just put on a washer and a clip through the hole. The bars on this seat do not have holes for the clips and they are not threaded. What type of hardware hold the seat back on? I took the seat back all the way off to inspect the pivot bar for any sign of a hole or other methos to secure the seat back.

Thank you.

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