Yes, that is the 4240 plow. It looks the same as mine except for a few minor variations..... probably just because of the possible differences in age.  One thing I found it that you will have to be cautious when/if using it on a newer tractor that has fast hydraulics. I tried it on a new JD5055 and the hydraulics are so fast that when I would get to the end of the field and go to lift it, the plow would really jump out of the ground.... the problem being that there is a little roller above the tail wheel and the tail wheel would override that and thus jam, then it would not lower properly.  If I idled the tractor way down and lifted a little at a time I could usually avoid the problem.
By the way, that JD is supposed to be a 55 horse tractor but the old Super 77 Oliver pulls it better!
Ill try to get a picture and post it tomorrow. It is out in the snow right now.
         Cal