Ron is absolutely right, I do have a photo. What you have is an early M group rear frame, that lug is for a tiny little side stand. I am pretty sure that these side stands are pre WM20 frames and as far as I know KM20 and earlier. These stands work very well but are not easy to find.
Thanks Henk for answering the email, I was at work and with the phone I could not replicate on the forum. However as I wrote you and I would like to participate in those who read the forum, I'm intrigued by this attack on a rear frame as I'm sure the bike is a wm 20 and not km .... thanks for the advice to recover a side stand that as I said .. today would also be comfortable given the roads we have, thanks to anyone else has to comment.
Marcoleo You might well have a WM20, but it could have been fitted with a KM20 rear frame at some time in it's life. Any chance of full side pictures? May help? Ron
I have a set of parts given to me by Steve Madden some years ago to convert a standard WM20 to use the small side stand, I'm not sure where he got it, but it may have been with one of Eric's North African shipments?
It consists of an over sized extra thick brake lever plate, and a rear torque arm with an extra lug, there seemed to be some form of spacer/stop missing to go in the middle which I didn't have, in this picture I have used a bit of tube to make up the gap.
The J11/12 replica clearly has a different bend. It would be interesting to compare the length, but think it is too long for the M20 as the pivot point of the M20 is placed quite low on the frame compared to the prewar models.