Hi all, I am restoring my wife's Bridgestone XO-1 which was kept in storage for quite some time. It is in excellent condition, however the rear derailleur is nowhere to be found. The drivetrain is Shimano 105 with a 7 speed rear derailleur and 7 speed bar end shifters. I have looked for a replacement 7-speed 105 rear mech to no avail, the only stuff available are 8 or 9 speed. Are these compatible with the 7 speed bar ends? Would the MTB derailleurs work too? Thanks!