If this part is no longer made, and you don’t mind spending a few bucks, look up local metal shapers, or hot rod/restoration shops that focus on metalshaping. DO NOT ask a welding or fabrication shop. Typically metalshaping and sheetmetal is not their specialty. I know of a few shops, besides myself, that do this work full time. Of course it helps to have something to go off of, such as the opposite side. Is the side you need to replace completely missing, or is there enough there to use for patterns and dimensions… or if you still have what’s left of this piece, perhaps it can be repaired.