I don't know very much about Campy's Delta brakes. I think they were released at various different times in the late 80s and early 90's and pulled off the market at other times when there were issues. From what I have seen on eBay, certain versions of the brakes are apparently more valuable and my guess is that this would be due to certain versions of the brakes being better designed mechanically. From a mechanical and perhaps weight perspective, which versions (years) of Delta brakes were superior, why were they better, and how can I recognize those particular brakes without having them torn apart to inspect the inside. In other words, what physical characteristics can I look for to identify the better versions of these brakes? Thanks for any and all input.