mugenextreme wrote: tallus man it is not hard at all. all it should be is strip out the two speed case from the main body of the truck, open this case up and you should see 3 bars all with gears. if i am right the bottom one has one cog and behind it is a kinda plastic disk with a bearing in it. u need to get out the plastice disc and there should be a slot then to fit in the module. the diff cup and the swing arm on the module should go through there slots in the plastic case then its just a case of replacing all the other cogs back in and closing it up . once re sealed attach the second diff cup to the bar sticking out to the case and that should be it.