I have been using Ultegra (9 spd) for the past 5 years. It is wearing out. The rear del. pulleys drag...I priced new pulleys...they wanted something like $40 for the set. I thought that was ridiculus. So, how do I determine which new rear derail. to purchase? I like the idea of moving to Durace- both for weight and bling. I see that there are several options. Can I use a "10 spd" derailleur on a 9 spd system?