Hi Edward , I am afraid I have no idea which type of derailleur would use this mounting. The boss itself however looks remarkably similar to a front lamp bracket mount, which your bike no doubt has on one of its fork blades. In this position it must of course be a derailleur mount ,but the resemblance seems a strange coincidence . The only other possibility although highly unlikely would be a chain case mount. It also seems to be rather high on the tube for a derailleur mount. One place to try would be the Hetchins registry, they have original build cards for many of the frames. A unusual fitting such as this may be mentioned on the card.
Greg Lone Langley B.C. Canada
---------------------------------
All new Yahoo! Mail
---------------------------------
Get news delivered. Enjoy RSS feeds right on your Mail page.