Is there any model#/year identification on campagnolo derailleurs? I have a set of 2007 Xenon ergo shifters and an unidentified year veloce rear derailleur (cheap ebay find from some time ago) along with a new Miche 9 speed 11-23 cassette. The shift increment is too far by a fraction of a mm. I'm wondering if I could have a pre-2001 rear derailleur. I ordered a new derailleur from universal and it looks identical except for the cage - old one has a cut-away on the inside, while the new one does not.

I am pretty sure the increment is governed by the shifter, not the derailleur... it is your Xenon shifters that need to match your Miche 9 speed, not the derailleur. The derailleur will only move inward whatever distance the shifter moves it. This is assuming your upper and lower limits are set correctly.

According to the Campagnolo parts catalogs only the rear derailleur design changed in 2001 and has a matching ergo shifter part for those derailleurs. I can't find anything about a different standard for campy 9 speed cassettes. The upper/lower limit is dead on, but each click is a little too much movement so it skips a cog after 5-6 clicks.

It does make a difference. Campagnolo changed the shifter cable pull and derailleur actuation ratio in 2001.

Al

Go on Sheldon Brown's website. He has all the cassette spacings in a table.

From the 2001 Campagnolo spares catalog
9 speed 1997-2000 Adjusting system on the upper body.
9 speed 2001 Adjusting system on the lower body.
You can download it here.
https://www.campagnolo.com/jsp/en/doc/doccatid_3.jsp

Here are the RD differences:

Pre-2001 8 and 9 speed rear derailleurs have a "B" adjusting screw that is under the frame hanger bolt and rests against the frame dropout. 2001 to current rear derailleurs have the "B" adjusting screw mounted on the rear derailleur body where it rests against the jockey wheel cage.