Xbox v1.0-v1.5 have MFG Date (manufacturer date) up to may 2004. Consoles with a later MFG Date are 1.6 version or higher. To be more certain you can check your video chip brand. Open your console and check your board, the video chip is located right behind the RGB/AV cable input. If you have Xcalibur written on it you have a version 1.6!
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