probably st-5600 shifters, the 10 speed where the shift cable exits the side of the shifter and runs in front of the handlebars. A quick scan of ebay shows they are available. You can also go with ultegra st-6600 which are one level up. 10 speed under the bar wrap (105 5700 and ultegra 6700) might work but Shimano modified the brake lever/cable pull ratios when they switched to under the bar tape routing so it might affect braking performance and require newer brake calipers.