Here a link to a Campagnolo Derailleur I have. This sounds a little like the one in question.
http://albums.photopoint.com/j/View?u=209617&a=10142789&p=34023306&Sequence= 0&res=high
http://albums.photopoint.com/j/View?u=209617&a=10142789&p=34023307&Sequence= 0&res=high
Perhaps our knowledgeable listmaster can indentify it. He sold it to me more years ago than I care to tell.
Karen Rawls
Winchester (cold and wet) VA