Saw this just a moment ago. Very hard to find if you're doing a 500! Burtons.......
http://www.ebay.com/itm/1957-Ford-Fairlane-Reproduction-Lower-Front-Quarter-Outside-Molding-Quality-/251486712819?pt=Vintage_Car_Truck_Parts_Accessories&hash=item3a8dc6b3f3&vxp=mtr#ht_2430wt_1224
Sure am glad that I don't need one.