This is one of the 3.0 Road Race series with the narrower downtube than the Criterium models. I have also looked at every catalog, and it simply isn't there. But this frame didn't come out until 1990, and the steel fork was used in the less expensive models rather than the alloy fork.

And the OP isn't the first to ask:
What model is this Cannondale 3.0 series bike?

I think that this was probably sold in 1990 or 1991, but wasn't advertised because the Exage parts were no longer current Shimano products. The components, though very functional, would have been considered a step down from the least expensive catalog model with Suntour Blaze. So I don't think they have a model number, or that number would have been SR100 because the Road Race bikes were odd numbers.

Really cool paint on these - especially considering the pricepoint.

These were surprisingly nice riding bikes, especially with aluminum forks. Really an improvement over the 1988 design.