I think the 28T derailleur has the long cage (a "Luxe" model.) The 24T derailleur has the short cage, and is the derailleur we all know and love (cage looks like campy nuovo record). Huret tended to offer long cages on all of their derailleurs, claiming that it extended the capacity of any given derailleur by 4T.
- Don Gillies
San Diego, CA, USA