Most M-400's in my area have Remote Ballasts and Remote Photocontrols...only a Few are Internally Ballasted with a Remote PC...and even Fewer with Internal Ballast and a Photocell socket on the Fixture itself.
Frederick has remote ballast of both silver and grey ones....in both remote HPS and remote MV ballasts.....but most of the MV ballasts are operating retrofit HPS lamps though..