Originally Posted by Gorsar
I think what nodnerb is saying is can he use the 8 speed shifters and derailleur but NOT use one of the 9 speed cogs, making the bike effectively an 8 speed. If that is the question then yes. There is also a very good chance (Depending on the derailleur) that you could use it for the 9 speed, in which case you'd only need new 9 speed shifters to fully utilize the bike as a 9 speed.
Yep. That's what I'm asking. I have 8 speed xt shifters/brake levers, and xt deraileurs still in perfect working and cosmetic condition. Plus they look and feel way better than the new xt stuff. I'm parting my other new bike and would love to swap all the new 9 speed drivetrain stuff from it and just use the 8 speed xt shifters and derailleurs for now. I actually can't ever see myself *needing* the extra three gears other than to keep it updated so I may never do it for what it would cost. I know the cogs are closer together on a 9 speed cassette so I was thinking it might not shift right into higher gears. Shifting from high to low gears should be ok I would think becasue you can adjust pretty much infinately with the thumb lever. Its up shifting where the steps are set to release X amount of cable each shift of the index finger I was worried about.
Thanks for all the help. Anymore info is appreciated.