The I2 is a 12.75 mm shaft like the Pred 314. The I3 is 11.75 mm like the Pred Z. I don't know that you can get it at 12 mm unless you got it directly from McD (where you'll pay retail) With the ICE core there might not be .75 mm to turn before you hit composite material. Maybe go with the I3 and have them switch it to a moori med rather than the soft moori.
You can get McD to match the rings for $15.00.
I have the Dubliner with an I2 with matching rings that I ordered from http://Billiards911.comand saved about 25% off of retail.
I want the I-2. That's the shaft that fit's me. I have my cue guy so I guess I'll have him cut it down for me. Thanks for the info. Still looking for an I-2........