Looking to upgrade the sx cassette on my son's bike to a gx as the sx has been nothing but trouble ,however I know I will need to switch to a xd driver freehub from the hg. Does anyone have any reccomendations? First of all the freehub body does not seem to want to slide off the wheel ? Any help or tips would be greatly appreciated. I see the fluid fsa2 has xd driver with the same wheel so it must be possible? Thanks!