67-69 convertible rear seat.

The rear back/upright tends to be in OK condition. Rust issues are found in the rear bench bottom. Parts from similar benches can be used for repairs. The only major difference is shape of perimeter frame.
In my experience, the sellers aren't willing to separate/sell their "vert" rear bench bottom alone at a reasonable price. I've seen a few of these rear benches offered over the years. I never see pics of where the rust issue is or isn't. One would need to cut hog rings and peel the skin away to show where the worst rust is or isn't. Good luck with it.