2 inches from that clamp on the engine side from the firewall side to the radiator support that dark line is the weld seam where I put that panel in. The panel actually came with the next fold in it down toward the frame rail. I trimmed it back and tucked it under because its easier to do the finish work there. If your rust is on the top where the fender tag washer bottle sit a partial panel will get it done, but if its down the side probably need a complete apron.