AC motor replacement of a D78 DC motor

We would like to get hold of the dimensions of a D78 motor and then find a suitable manufacturer of 500 kW AC traction motors to replace the DC motor.

We manufacture traction inverters using direct torque control. We are sure that the only way to upgrade a locomotive from DC to AC is to get a motor that can be directly retrofitted to the existing mechanical housing.

I would welcome comments on this subject

The D78 is an EMD TM, not used on Alcos. Perhaps this question would be better asked on the EMD forum-