I know the mechanical won't fit the electronic shaft, but are the gears themselves the same size? There's a lot that can be done with a lathe and a mill.

Yes.

The drive gears are all the same dia as well. Although there's only about 2 or 3 of those that were used in our particular applications AFAIK... 7 & 9 tooth are the only ones I've personally experienced. Driven are around 18 - 21 teeth, and the ones for different drive gears are different. (different tooth angle according to the pitch of the drive gear)

I need a brown 18 tooth driven, and I know I can only find them in the mechanical variant. I just changed the drive gear to the blue 9 tooth. I removed the red one that was on the T5. I have a 3.27 9 bolt, so I ultimately need a 9/18 setup.