Just buy the teknorc battery tray, esc mount and the rcm motor mount.
The Tekno RC Battery Tray for Revo will bolt on to the chassis of your Revo 2.5 or 3.3. It will take the place of the fuel tank and right side radio box. It can be used in conjunction with other conversions besides the Tekno RC Brushless Conversion for Revo.
Durable injection molded Delrin construction will handle most any situation. Accommodates batteries up to 150mm X 50mm (although we have seen slightly bigger batteries get squeezed in). The height is limited only by the body and straps you choose. Batteries that are too big will make the vehicle unbalanced however. Anything below 600 grams is recommended, which leaves a lot of options.
