I found the one I was looking for. It was an old Rocker catalogue that should have been (and now has been) tossed 3 years ago. But you know how it is when you could swear you've seen something and then you do start swearing because you can't find it.
One comment about mobility chairs and casters, I'm noticing that most of the casters have mounting plates rather than stems. But it would also seem to me that you might want a lathe chair to be a bit taller? So plate type casters could be mounted to the underside of a board and the chair, with original casters removed, mounted on top.