There were a couple versions. Mine is a single arm on a Record
derailleur(1963) with one Cyclo and one Benelux pulley .Later ones were
double sided and used the Campy pulleys.
First Rally derailleur I saw was 1973/74 at Fulton st cyclery in SF
and I recall it came from the Taylor bros in theUK
BOB FREITAS
gray overcast in PETALUMA,CA USA
former Egg capital of Norcal and home to many Jewish egg farmers
in the day