Some post type vises don't have legs, some have been cut off. For $48 I'd take it even without a leg. They have some that were for wagon tongues. Fisher made several screw type chain vises without legs.
The only thing I'd really look for is wear in the screw. Getting parts is pretty hard(impossible) they can be fabbed and if the spring is weak, bad or missing it can be easily made. I've got two post vises, and have seen 10 or so others in the last year , and not one was the same...
I honestly just can't say no to "deals" on old blacksmithing tools....