I am redoing my seat in my 57 3100.
I have a vinyl covered "behind the seat cardboard" piece that I want to attach to cover the seat back springs.

But I am not sure how to actually attach it. I think the vendor said to use screws and stainless steel grommets. But I do not see any way of doing that unless you are suppose to screw into the seat back steel tubing.

How did it use to be done back in the 50's?
Was there some type of clip or something?

If it is screwed what is the location of the screws and how many are there?

Does anyone have a good picture they could share showing the setup, locations and number of fasteners?