These are the highest level, shimano compatible, grip shifters available that I could find new: http://www.niagaracycle.com/categori...st-shifter-set. They are friction front and will work with your current rear derailleur. The MRX series shifters are also compatible/available new, but are lower level. Any of the shifters that have an "X", like X.0 shifters, will not be compatible with your shimano rear derailleur. To use those, you will need an "x" series Sram rear derailleur (the cable pull is different). Also, any ESP series or numbered (i.e. 3.0,4.0,etc.) grip shifter will not work with a Shimano rear derailleur. Just make sure that any set you buy has a 2:1 cable pull ratio.