Rotary Encoder w/ Dual Flatted Shaft

[knossos]

Anyone know of a source for rotary encoders with a dual flatted shaft (A shaft like an I instead of like a D)?
The shaft needs to be approx 3mm (1/8") in diameter, with the flat part about 2mm wide.  The encoder base should be no larger than approx 14mm square.  Magnetic encoders would not work, but beyond that my specs are fairly flexible.