Given the serial number I would guess 1989, they made aluminium frames later in the 90s. I am not familiar with their serial number convention, but I would refer to some catalogs that have your model in them with the same component group. Also, if your components are original there are more than likely manufacturer date codes on them that usually will be the same year as the bike's year of manufacture or maybe a year earlier. Note: the bike's year of manufacture might not be the same as the bike's model year since next year's models are being producing prior to the calendar year of their catalog. E.g. if a component date code translates to 2000 the bike's year of manufacture would probably be 2000 or 2001, and the model year could be 2000, 2001, or 2002. That is when you can usually refer to catalogs, if available, to pinpoint a model year.
If you post a complete drive side photo of the bike it might help us to help you. More photos with details even better.
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