I've used Campy 51,50,49, and 48 as high gear for years. The only thing
about "rare" is, it may raise the price. I believe 52-42 must be
"standard"!
I've even seen some "rare" SunTour Cyclone deraillures!
The best one I've seen is the Dia Compe canties that fit old Colnagos!
Dickey Greer
West Monroe,La USA