The people at MTH would have to take the approach of making a new version of the SD40-2 that has railroad specific details in both HO Scale and O Scale first, then S scale and No. 1 Gauge.
They need the General Motors Diesel Division safety cabin with 4 windows option.
They need dynamic brake options.
There has to be distinct styles of grills.
Not all the headlight positions would be the same.
Andrew