I have an old Performance Aurora mountain bike that still serves me well. I really like the bike but I need to replace one of the thumb shifters. It's an old Shimano 200gs thumb shifter. Does anyone happen to have a pair of these in decent shape for sale? I really need the left side shifter/brake lever unit, but would buy both if you have them. I've looked everywhere and I can not see to find them. Any help here would be appreciated!!! Please PM me if you have these!!!! Thanks!