Going back to the esc mount location you can use the mount from the caster Fusion, its fits to the back on the centre diff mount without any modification to the MBX5
http://www.junction8models.com/epage...oducts/EX-0507
then use the esc clip from the traxxas and you have a factory esc mount solution :-)
http://www.amainhobbies.com/product_...late-BL-E-Revo