There are no external differences between a 764 the has the embedded audio option and one that doesn't. The way to verify if option 01 is installed is to press the MENU button, and then scroll down to the INPUT submenu. Push the SUBMENU button in next to the lower right corner of the display screen. The INPUT submenu will be displayed. Choose the AUDIO SOURCE menu item and see if DIGITAL VIDEO INPUT is an option. If it is then option 01 is installed. If option 01 is missing then it can be added by ordering an upgrade kit (764F01).