DIP-8. There is no such thing as DIP-3, AFAIK.
Whether the opamp will clear the case or not depends on the case itself. A few lucky individuals have no problem on clearance on DIP8 opamp, but most of us do and need to mod our case.
The instruction is on page 30, but here it is again:
In the spirit of DIY, I took the time to sand down the case so it will accommodate a DIP8 packaged opamp better.
I used some masking tape just to mark the area that needed to grind down. You will have to go about as deep as the microUSB opening, around 23mm or so.
I took out roughly 1mm or so in material, basically half-ing the overall thickness.
Now the DIP8 opamp sitting flush inside the case without bending the PCB or applying any stress.
Edited by ClieOS - 5/13/14 at 8:20pm