Again, thanks for the reply. I just recently managed to pick up 3 of these kits - one twinpack and the other a single. In the twinpack there are extra parts to top the bunks for the "plain" version of the car - but weirdly only enough parts to do 1 car! The other single kit had no such extra parts. I've previously made the rail version of this car a few years back, so I thought a plain version would be good. Just a bit surprised that Hartford weren't consistent with the contents of the kits!
I feel fairly happy with the general arrangement of a plain car, although the instructions say that some or all of the end and centre (smaller) bunks can be left off, and I would have liked a picture reference to be sure. I can find plenty of pics (and a photo!) of the rail version, but drawn a blank on the plain one.
Looks like everyone builds the rail version!