So that's an original radiator huh?
That is a Harrison radiator which is one of two different types of side mounted radiators used in CJ-3As. The date code 52J means it would have been originally installed in a late 1952 or early 1953 model year vehicle. The vehicle serial number, engine serial number, or a photograph of the dashboard, or inside hood seam, can be used to determine if that is a late '52/early '53. If the starter that's laying on the battery tray fits it is late '52/early '53.