seat backs questions

I have just bought some deluxe seats and thought i was going to have a nice easy job popping them on, but (as usual) nothing is as easy as i hoped.

I have these metal seat backs (which i can't find on the S3 parts list) which i can easily bolt to the (sliding) seat base frame. I thought i would just pop the seats onto the seat backs.

However, the deluxe seats are at least 4mm wider than the gap between the two sides of the seat backs. I could force them on, but that is likely to do some damage and i can't believe is the right thing to do.

Looking on Youtube, it looks like i don't need the metal seat backs - I should discard these, and just bolt the deluxe seat back directly to the seat base frame.

I think i would need to use two bolts on each side, so that the seat back was in a fixed position: i am a short person and need the seat moved as close to the pedals as possible, with the seat back similarly forward. If i just used one bolt on each side, the seat back would rest on rear bulkhead and i would not be able to easily reach the steering wheel.
The metal seat back is obviously strong and with two bolts on each side, it would hold a seat back firmly in place. I am hoping the deluxe seat is sufficiently strong to stay firmly in place if i use the 2 bolts each side.

Can anyone explain why my car had the metal seat backs, and confirm i don't need them if i use the deluxe seats as described above?

Many thanks

We put deluxe seats in the 2a. Can't see how they would be strong enough as the lower fixing bolt is more like a swivel so you can fold the seat forward. The seat rested against the stops on the rear bulkhead, truck cab, when upright.

An old seat I removed had a metal back and as I recall had those holes in them , perhaps that’s the remains of the old seat.
So agree don’t need them I have deluxe in mine secured just using top holes in side brackets , allows you to lean them forward .
They do also need to be secured to bulkhead by the leather straps otherwise mot fail

Have you got the seat runners adjusted fully forward using the lever
Excuse the manure in pic

Re with @stave2286w above, It is the angle in the bracket [ pic 3] that prevents seat back from folding back when seat moved forward.

I have removed the metal seat backs. I have installed deluxe seat with the single bolt on the higher setting each side. This holds the seat in and I can find the seat down. I have the stops on order. I think with these in place, the seat back will be in a position that will allow me to comfortably reach steering wheel when the seat is slid into the forward position.
In terms of the leather straps, is there a nut hidden inside the back of the seat somewhere that the strap attaches to?

For the little, middle seat, am I right that there is no bracket, the base and the back just rest, with some leather straps to stop then flying around?

I bought a suitable belt from charity shop made my own straps , self tapped into back of seat
Middle seat back has some studs either side which fit in the two side brackets, secured at top with the straps the base sits nicely in the base frame
See if I can add pic tomorrow

I am going around in circles a bit.
I have sorted the drivers seat - will fit back stops and leather straps to finish off.
Am still confused about middle/passenger seats.
Having dug around in my photos during dismantling, i can see (in first photo below) that the middle seat had these brackets.
At the moment, i have used these brackets for the passenger seat (see second photo).
So i can remove these brackets and use for middle seat - fine.
But then what do i do on the passenger seat. I could bolt the seat base bracket to the seat box, but then i wouldn't be able to open the lid of the compartment. I don't have a photo from "before" to know what to do.
I have dug around in my list of remaining parts, and i can't find any other seat brackets.

The middle seat bracket looks like you have that , the white bit, the seat back should have two studs sticking out that go through the holes either side , just prise the brackets apart , won’t need to use split pins

The passenger and driver side just a mirror image of each other, last pic should be able to see it all

I put a set of sliding seat frames in my 2A, but found that they just took up more space, and made the driving position even more cramped.
I'm 6' tall, so there must be plenty of owners with even longer legs than me.
I ended up removing the adjustable frames and going back to the basic set up - it really suits me better.