dura ace 7400 help!!
 

I am currently working on a 1990's cannondale I am building it with dura ace 7400 components and I'm planning to put the rims I have wich are made for a 9 speed cassette. My question is: Would the 6 speed dura ace 7400 cassette would fit on this hub? or would i have to change it? since i was reding that the forst cog of the cassette is treated and the other would slide in. Please help.

no, 9 speed will be hyperglide, 6 is uniglide. See here:
http://sheldonbrown.com/k7.html