In the Virus Definitions & Security Updates webpage (link: http://us.norton.com/security_response/definitions.jsp) Norton 2013 products (NAV2013, NIS2013, N360 2013) are missing from the 'Select product' dropdown list.
Also in the download webpage (link: http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=n95) Norton 2013 products are missing from the supported Symantec antivirus softwares list.