Triple a metal finishing in St. Paul or Minneapolis not for sure but I do know there the ones that made the Model A bumpers for little Dearborn, there NOT show quality or anything not even close to being show quality they don't look like the originals did.
But they might also be the ones that make other bumpers as well you never know tell you talk to them, you will have to google there phone number or North Star Plating might also be a place to call as I know they refinish a lot of bumpers there more then most.
Reggiedog