Are you talking about 'water hogs' or what? Neenah Foundry out of Neenah, WI has many castings available and if the market is large enough will design a new one for you.
Apparently, there are trash racks manufactured that can be installed in gutter inlets, an NJDOT 'B' inlet, to facilitate the removal of debris. But I don't know who manufactures them or if they even exist.
