Replacement brushless motor shaft material

[Hiphopbots]

"NTM motors in argos gearboxes "

I assume it is this drill: http://www.argos.co.uk/static/Product/partNumber/7112946.htm
Did the pinion gear fit from the original motor og where did you get a matching pinion from? and how was the mounting onto the drill gearbox?

I would like to try brushless drive also