Does the center diff assembly fit without the center diff riser? With the recess machined into the chassis, it looks like there would be enough room for the spur gear, and with the Grid mount, the motor wouldn't touch the chassis. I'd just try it, but I thought maybe someone has already tried, so that would save me a bit of work.

not sure about that one. I havent tried it, but its the Nitro Chassis so I think the recess was for that portion of the buggy.