Sorry if this has been posted elsewhere but I couldn't find the answer using the search function.
I have an Ultegra RD-6500 rear derailleur which currently has a cracked guide pulley. I can buy new pulleys but they tend to be quite expensive for an RD-6500 set. In fact, RD-6600 and RD-6700 pulley sets are about half the price.
I know that RD-6600 and RD-6700 are designed with a 10 speed in mind so perhaps the pulleys are a bit different (perhaps thinner).
So my question is are RD-6600 and RD-6700 pulleys compatible with the RD-6500? If not, is there a generic source for RD-6500 pulleys or is it best to just bite the bullet and buy the expensive Shimano RD-6500 pulleys themselves?