What model-year R900 is it, and what frame version? (Unless it's been repainted a different colour, you can usually work it out using the older models catalogue on www.cannondale.com and matching colours with your bike)
Is Shimano 600 the older/another name for the Ultegra level?
It's original paint and I believed the model year is 1997 and the owner hardly use it since it's the display model, the shimano 600 had changed to Ultregra that I was told.