C-10 middle buster mounting questions..

When I bought this I was told it was a Lister unit. But I now am pretty sure it is a C-10 middlebuster. It came with the homemade unit in the photo plus the busters. This is my fist time mounting anything to my SC and it took me quite a few hours. I am glad I had a book with photos. To begin with the 'J' bolts were installed the wrong direction. Heck I didn't even know which way to mount the axle clamps. The problem I am concerned about is the 'J' bolts. If I tighten them they slide off of the hook and if I leave them as is there is a gap (see the white arrow in the top photo) at the hitch point. Also the manual says to put the bolts for the hitch bar in the center hole in the rear support. When I did this the unit would not attach. I had to move the bolts to the top holes. Is this a potential problem?
All that being said I have used it as is and it seems to be working ok. It did not come loose at the hitch point. Also I have just realized today that that tool bar can and will be quite handy. I was running around the shop looking for something to mount to it. When I figured out my planter will, man was I excited...

You have the wrong nuts on your J bolts, they should have a tapered end on them like you see on a wheel lug nut. the taper fits into a pocket on the fork the J bolt slips onto.

Well thanks Handyman.
Now that you mention it, the drawing in the manual clearly shows conical nuts. I will have to find some today.