I just added a stem extender and trekker bars to an old hardtail mountain bike with twist grip shifters, and I need to replace 3 of the cables and housings because they're not long enough. (For some reason, the existing rear brake cable and housing seem to be ok as is... There's not a lot of slack in the housing, but it seems to work.)

I bought a couple of these brake cables and housings: http://www.amazon.com/gp/product/B000C128MK, and was wondering if I could use one of the cables (not the housing) for my rear shifter. I have a set of brand new (Campagnolo) shifter cable housings that are good quality and can be used, but am short one long cable to use for the rear shifter.

Is there a difference between brake cables and shifter cables? Do I need to buy a shifter cable? (Normally, I would just go ahead and order one, but I'm anxious to get this bike back on the road...)

Thanks in advance...