after taking my d3 apart and putting on my duo2 endbell I can say that they are the same. even the sensor plate has the same markings and if the sensor is as I suspect it, it has the same position as the 2. now the holes in the can and the new sintered rotor instead of the plastic coated one in the 2 is probably making it a lot cooler running motor. but the problem with that is with stock spec you get too high a FDR and it still bogs. but in open ESC I bet it will be sweet and even in stock spec it seems to be running considerably cooler then my duo2. this would allow it not to fade as much as the duo2. one thing I want to check is the impedance compared to a duo 1 or 2 that would clinch it for the stator being the same also.
I think I'm going to take the rotor out of it and run it in my duo2 and see. and then swap it for my duo 1. turbo dyno here I come.