Chas stated:
I've never seen one of these derailleurs on any other bike but a
PX-10.... referring to: http://tinyurl.com/
Chas and list:
I purchased a Follis 172 in 1975, that a good friend still has. It has the exact derailleur. The date of manufacture may be earlier than 1975 as Phoenix Cycles in Carbondale, IL had to work off a large inventory at the time.
Ken Wehrenberg, Hermann, MO USA