Slant 6 Exhaust Clamp.

That is an original hanger. If you need exactly that part you might try Accurate Exhaust. They make repro exhaust for our old Mopars. Classic industries may have something as well. If originality is not important, parts stores have universal hangers that will work fine. If you are looking for a used original piece, you need to start a want ad here on the site. Wanted ads work for new or used parts.
Great information! Thanks!