It's easy to forget that, back in 1990, Campagnolo sponsored professional mountain bike teams that actually won races. Tim Gould and Cindy Devine were shifting with a shiny Campagnolo Euclid derailleur.
Browse associated derailleurs.
Campagnolo Centaur (Q010-MD) 1989
Campagnolo Centaur (Q010-SM) 1990
Campagnolo Euclid (M010-MD 2nd style) 1990?