Picture 1 shows one of four seat ribs with the seat belt parts attached. All parts are handed so is should be difficult to get it wrong.
There's lots of work riveting nutplates to the seat ribs here. They are all different and it is quite difficult to keep track of which ribs need which work to be applied. There are four ribs per seat, three of which form one sub-assembly and one which stays unattached at this stage.
