* Most Campagnolo rear derailleur parts can be interchanged amongst Record, Chorus, Centaur and Veloce rear derailleurs. 
* Campagnolo Record and Chorus rear derailleur cages are interchangeable. So are 2004 to current Centaur and Veloce rear derailleur cages. However, you may not switch a Centaur cage with a Chorus, nor a Veloce with a Record. Record and Chorus cages bolt to the rear derailleur body while all years Centaur and Veloce cages affix via a small "C" clip. 
* Pre-2004 Centaur and Veloce rear derailleur cage assemblies used an all metal cage assembly pivot adjusting housing and screw (part L above). 2004 to current Centaur and Veloce rear derailleurs use a black plastic pivot adjusting housing. The two types of pivot assemblies are not interchangeable.