[RC-Monster Mike]

Cool conversion - I have a comment on your rear motor support, though. I think it is a bad idea. Any flex in our motor mount will be pretty minimal, and the entire center diff assembly will "flex together" as a single unit and maintain its integrity without the rear support. It will flex far less than the chassis itself in actual use for sure.

In use, the chassis will flex at the point between the front of the rear chassis brace and the back of the center diff(where there is no bracing) - this causes the rear of the chassis to flex independently of the motor/diff assembly all day long - by supporting the rear of the motor in this area you are introducing excess force on the rear of the motor, and therefore the motor mount, motor mount screws, etc. (when you land a jump, for instance, the rear of the chassis will flex upward and push the rear of the motor upward - twisting the motor and motor mount far more than it will flex on its own).
This forces the motor, motor mount and motor screws to absorb the load of the entire truck as it lands and the chassis flexes, instead of only the weight of the motor(the motor and motor mount are now a chassis brace). Part of the idea with our motor mount strategy is to keep the motor and center diff together as a single unit - independent of chassis flex.
I think supporting the rear of the motor like this will create a problem in the end - perhaps the motor mount screws will be the breaking point, but the motor mount and motor itself will likely take the most punishment (the aluminum motor can will take a lot of force at the mount screw location).
Anyways - just food for thought. I just figured I would take the opportunity to explain the thought behind my motor mount design strategy, and why I think this particular rear support implementation it is a bad idea. :)