i think the left one is a KR557 8 drawer box. it is only 32" wide. notice the height difference between it and the middle. there might be a newer, kr657 version with roller bearing slides. not sure.
the middle is either a KR555 8 drawer, with friction slides, or a KR655, with ball bearing slides. interestingly enough, if it is a KR555, there will be dividers in a bunch of the drawers. if it is a KR655, there won't be any, at least that is my experience.
i have one of each of the "55" models. if the middle box is in good shape, and it certainly looks to be, it is not completely unreasonably priced, at least for around here. if he was within two hours of here, i might be talking to him (like i need more of those boxes . . . ) and see if i could talk him down somewhat. the "57" box is likely worth less than the "55", but, again, it looks like it is in exceptional shape.
anyway, those are *great* boxes. i am really happy with mine. the "57" is comparable, i would expect the same satisfaction from it.
replacement friction slides are still available from snapon, but not the tracks they run in. i dont know about the roller bearing slides, accuride probably has something, though.