Yes they are steel and one is broken and the piece is missing , the others are intact. During disassembly of the seats I found them laying on the floor and have yet to figure out where they go .
I'm not dressed yet. I've got a set of '64 Barracuda buckets in the garage. I'll have a look later today & see if I can find anything like that on them It's 3 degrees out there right now so I'm not in a big hurry. LOL
On 2 door cars those springs are used to semi-lock the seatback in position when they're fully upright. Kind of a precursor to the later fully locked setup they used later & an all new cars.
That's sounds about right. Been a couple years since I played with those seats & I don't remember the exact setup. You'll need to use some trial & error to get it right.