There should be no gap between the floor pan and the brace. I suspect the quality of the install is poor overall. Depending on the condition of your bronco it might be fine, but if you have a nice solid truck then I would redo them.
I bought my first bronco last summer and the previous owner replaced the floor pans and did not know how to weld. That and the brake booster bracket he made were worse than my worst welds ever. I chose to get the factory lookin pans and redo them myself, correctly.
So if you can live with it, leave it. Otherwise order up some new ones and have an experienced person do it right. I figure that they wont be as strong as intended without being welded to the supports.
