Not a direct replacement for a shop/repair manual this self study manual will give you a break down of all components and systems, realistically its a step below the shop manual but still a great way to get intimate with your Duke 390....
http://www.ktm.com/fileadmin/user_upload/eAcademy/Download_Centre/SSM_902_EN.pdf
http://www.ktm.com/fileadmin/user_upload/eAcademy/Download_Centre/SSM_902_EN.pdf