One of my small projects is for ESC and radio mounting plates forward and aft of the center diff.
The ESC will be mounted behind the diff between the batteries. And the radio tray will be mounted forward of the center diff between the motor and the steering servo.
the ESC tray needs to be 45x140mm. It would extend from the center diff to the rear bulkhead, tying them together for extra rigidity.
The radio tray would extend from the center diff bulkhead to the front steering brace.
Essentially tying the entire chassis together like a double decker chassis.
These would just be flat rigid plates in 3mm. Nothing super special.
See below pic.
http://home.comcast.net/~thirdgen89g...crt_plates.jpg