Just to be clear, you don't need the Brushless support to mount a brushless motor. This item only raises the central axle by 2mm so you can use bigger spur gears. You will need that if you are running a 4.5T because you will need a 1:9.5 ratio and a huge spur gear.
If you are running 21.5, 17.5, 13.5 or 10.5 the standard support is fine.