[Dafni]

Yes, Mikes' mounts will all have the mechanical brake option before long.
The XT8 mount will hit the shop with the option, and all other mounts will change later on.

Chassis brace is just a plate, bolted to the chassis under the center diff, servo and another hole in the rear (where the stock electronics box was) You can see some contures in that other pic I pointed out.