so i'm upgrading an old Puegeot from downtube friction to ergo index shifting. i'm ordering new derailleours, cassette, and shifters, but my Q is this: anyone know a rear derailleur that can mount to a Peugot frame? its old, late 70s maybe, and the right drop has a specific ring for the Sachs/Huret derailleur to attach to. i though, hell, i'll take the Shimano rear derailleur and throw that bad boy right on, same with the front, grab some new egro shifters, and all i'd have to worry about was the cassette, boom-bam! indexed peugeot! but...the shimano won't screw on with ANY clearance whatsoever. anyone know of derailleurs to fit with a french frame?