hello all. i have a hj47 with drum brakes on the front end. i have recently bought a hj75 and i want to put the disc brakes in it into the hj47. im a bit of a dopey fella so i need to know everything that i need to take out of the hj75 for the conversion. someone told me i had to change the master cylinder? and its easier to change the whole axle than just the brakes? it would be much appreciated if someone told me what and how to do. thanks.