I just measured mine at 57mm. Which works out at 2.24 inches.

Thanks. That is the exact depth of the old r7 Quad.

I just made that exact switch to the 910 D3.  The 910's RIP is a real RIP shaft (not a "made for TM") and at 63 grams is a lighter shaft which increases my swingspeed to where an "easy" swing is still under control, while maintaining the low 2.9 torque.  Not sure exact dimension, but face is definitely not as deep as the Superdeep.   Demo the Titleist!  I went through 3 different R9 drivers last year, ending up with the Superdeep, and the 910 D3 is more reliable for me.

Thanks. That is very good info. I know I am probably going to end up with the D3, its only a matter of time. I currently have a Proforce V2 96 gram stiff shaft, and my swing speed varies from 108-118. I like to play a cut, and the tip on that shaft is 1.7 which helps cut down the spin, so 2.9 is not low enough for me, if I go with the RIP, I may go with the 70 and x-stiff which gets the torque down to 2.2. Thanks for all the good info, I know it will make a difference.