Some of them came stock with the sofa. I would've went for this when I bought my 2007 2600 SO, but the dinette is a far more common layout. If you replace, make sure the sofa isn't a lot heavier than the dinette. The slideout is sensitive to this, which is why they have a sticker on the bench seats that say not to use the open area under the bench for storage (but we do anyway
).
No comment on the flooring.