John,

There is no staple "best shaft" that goes with the 909 D2. I would have to say that your best bet is going to be getting fit by a Titleist dealer with their FittingWorks system to find YOUR best shaft with the D2. If that is not possible for you, under the drop down golf clubs box on the main Titleist website, there is a "Selector Guide" that can assist you in finding the shaft you would best fit into. Click on the "909 Driver Specifications" and they provide a PDF format of all the shafts and specifications on them.

Hope this helps and keep them in the short grass.