Just to clarify, this pedal does not thread into the crank arm, and does not have flat cut on the boss that engages the crank arm mounting holes.
The crank arm holes are circular cut at .562 inches dia.
The circular boss length prior to where the threading begins is approx 3/8" long (thickness of crank is 3/8").
The threaded portion beyond the boss/crank arm is 1/2 x 20 tpi.
Thanks again, Kurt