I just purchased a new 915 D3 to replace my 910 D3 based on the lower spin rates.  I am having a problem though.  I put the shaft settings the same in my 910 as on my 915 and have a totally different ball flight.  The 910 is strait to having a slight 10-15 yard draw.  The 915 I hit it strait or a left to right back to target fade and about 50 yards shorter.  So I thought it was the shaft.  I put the shaft from the new 915 in the 910 and had the same ball flight.  Ok.... So I put the 910 shaft in the 915 same test.  Same left to right ball flight and shorter. 

Did something change in the shaft settings? I will preface that I got the 8.5 in the 915 but I have it set at B2 to put it at 8.5 and the 910 was at C2 8.75.  So I figured I just had to get the lofts pretty close to one another and would achieve the same ball flight just slightly, then take the new 915 back down to C2 to achieve the much lower ball flight and more run out that I was wanting.  I am at a loss.. I will say that I am seeing more run out where as with the 910 it pretty much stayed where it landed usually 10yds of roll out. I have a fitting tomorrow with the club pro to work it out, but I wanted to know from Titleist is something changed in the dynamics of how the shaft inserts into the head? We are also going to try a 9.5 and see if that helps and if so swap it out. 

Any feed back would be appreciated.