I have been playing an 8.5 degree 913-D2 with the Diamana ahina 72 shaft. I was fitted by my Titleist rep and have had great success with the driver. I recently purchased the 915-D2. My local dealer did not have the stiff shaft so he let me keep my Diamana on the new driver while the new shaft comes in. However, looking at the stock shafts available on the 915 I cannot determine which shaft I should be playing. Can you help me determine which shaft will most closely match my old Diamana?