I have a Zeus alloy 6-speed freewheel I got at a local estate sale for a dollar, it belonged to a guy I used to know who raced bicycles thirty to forty years ago but died of pancreatic cancer. Also got his metric wrenches and a pile of nice bicycle books. Next riding season I may try the freewheel out on one of my old friction-shifting bikes just to see how it shifts. If you figure out a price for this derailleur pm me and if I have the money I will consider buying it, but sorry I have no idea except that it may be worth as much as a Campagnolo derailleur from the same year, that is what it sort of looks like, a Campy copy. If it shifts as good as the Campy and Shimano equipment contemporary to it then it would be useful to boot. A lot of the oddball stuff did not work as good as the Shimano, Suntour and Campy stuff. If you have a bike it will fit try it out before you get rid of it.