One more area to address in the pursuit of saving center drives. There's a gaping point of access for rocks and things lurking under the motor. One would think there's too little room here to do much, but turns out there's plenty of space.
Obviously my center drive has seen quite a bit of action (the black sticker around the underside of the motor is torn up as well).
Blanking panel prototypes:
And final version, cut from a thin flat part of a clear plastic container (strawberries or something), scored and shaped for a tight fit, and held down with double-side automotive trim tape. If you run a big spur gear, you'll probably need to be careful about thickness and shaping in that area.
Ran the car hard Rallycross style and the under-motor shield worked great. Still getting small abrasive bits in around the transmission output, so added a little more foam tape, should seal the center drive off almost completely now.
Center drives and diff housings seem to happy and well-protected from the abuse. Still have to stop pick stones out of the motor pinion and big spur gears (and sticks out of everywhere else).