All the arms work with all the spindles. The interface has never changed, going all the way back to the first Hollowgram and including the old three-piece Carbon SI crank (there was a two-piece version that came out in 08 or 09).
You are more likely to need the 109 vs. the 104. There are spacers to run on the 109 if it's too long. If you are unsure which you need, you are better off getting the 109 over the 104. I don't think Cannondale even makes the 104 anymore.