Originally I did not plan to create any building instructions for this mod as the motorization was an ad-hoc process, tried to replace the manual parts while keeping the original structure as intact as possible. Since I received so many requests to provide instructions, I try to help you and took a series of pictures while disassembling the model. Please note that this video is far from being a complete guide – it shows how to build the 2 axles and provides some additional hints on the placement of the M motors.
If you’re looking for 3d files or additional ideas to motorize this set, I suggest you to check this topic on Eurobricks, it already has some great content and I’m sure it will have more.
Great, glad to help! 🙂