Vintage Cannondale usually has replacement cable guides, but when I looked for my brother's bike the other week, they were sold out. Pretty close match and easy to install. If you want to push out those nubs, you'll have to drop the fork to get the little plastic bits out of the top tube as the top tube only opens into the head tube. Otherwise, they'll just be jingling around in the top tube. They're a close match to the originals, but slightly larger. You'd only notice if you were looking for it.