Thanks.
Got it, your top bracket is slotted left to right allowing the corner of the blade to raise to adjust to the cross slope.
I see you like painting about as much as I do (I don't mind the painting, I just hate the rust removal and prep to do a good job.) My grader attachment is still in the shop. I needed to do a couple of repairs and my buddy shamed me in painting it with the comment "You already have it taken apart, you might as well paint it." After the degreasing, pressure washing, grinding and needle scaling done a little at a time over the summer, it got too cold to paint it. So I warmed up the shop enough to spray a light coat of quick dry primer on it. It is still resting on dollies in the shop...