Well I guess someone might know, but I doubt there's a Douglas guru alive who could list all the models of the top of his/her head. I know I could find out - it would probably only take an hour or so to look at a bunch of catalogue illustrations (which are often wrong), parts lists, period photos and so on. We could come up with a reasonable list.
But do you really need to know ALL the models that used the saddle mount on the top bar? Or maybe there's an easier question you could ask. If it relates to a bike you're restoring, let us know the frame number.