The large keystone badge with Chicago on it instead of Monroe is what dates it (84ish). Before this badge, Ludwig was using the Blue Olive badge. The black face P85 strainers were used in the early 70's. But many of these late Chicago drums have the 12 hole black face P85 strainers. Most likely a case of Ludwig using some old inventory that they had before the move to Monroe. Ludwig was known to not waste materials.
Mike