Remember Matchless used a similar [same?] clutch, some parts from earlier[pre AMC]Nortons are nearly identical,[and throw in the Atlas],and also mods sold only on the US market for bikes like the G15CSR and P11 Ranger, and the small thing of forty years passing,and who knows? Old bikes are the art of the possible,perfectionists who memorize parts lists all night are ok for info,but don't take too much notice of them.Strangely ,the same person who picks all sorts of faults with your bike will then turn up with an electric starter fitted to his allegedly "correct " restoration.Regards John.