I took the Huret Allvit off my Nomade to check and found the dropout is perfectly flat as I remembered. I cannot explain why yours would have a bump there. The photo is too blurry to make out what it is. Does it look factory?

The Huret ECO S is a very nice derailleur. I wish my Nomade had it. My Peugeot has it without the hanger or claw.

Nick Burns link does show it but for some reason the photo of the ECO is minus the gray plastic covers. I think the S just means Sachs after it became Sachs Huret. Here is someone in your neck of the woods selling one on eBay.

http://cgi.ebay.com/SACHS-HURET-ECO-...QQcmdZViewItem