Okay before this gets out of hand I'm finishing the starter debate with a simple equation (me + 2 6v starters + no money for a 12v starter = sticking with the 6v starter with 1 extra replacement for oh crap situations)

Can anyone explain the 12v internal parts for the 6v generator for converting the excising 6v to a 12v while still using the housing?

Has anyone done it?
Is it something the amateur mechanic can do?
Or should I just buy a 12v generator to start with and jerry rig a bracket?