Thanks Rik, That's a post war cap but Ian said the chain cases are different, I know the drain and fill caps are different but the tin ware is or looks the same as war time I think,Andrew.h

email (option): warbikes@gmail.com

There is a metal band spot welded around the edge of post war cases after 47..If you look closely you can see what's left of it on the photo posted (at the top/front of the cover). This is not present on wartime ones and it has to be cut away to clear the crankcase breather if fitted to earlier (Girder Fork) M Series bikes...Positions of the footrest holes and level plugs also vary from model to model....
On the inner case the position of the piece that the chainguard attaches is also different for various rigid and plunger models....Ian

email (option): ian@wright52.plus.com

Thanks Ian that sorts that out, Andrew.h.

email (option): warbikes@gmail.com

At some point in my M20's life, the cush drive nut has come loose and damaged the front cup. So I thought I'd just fit a better cover. Bugger me I looked at loads of them and actually bought three wrong ones!! There are so many variations of them.
In the end, Ian gave me a scrap cover with a perfect front cup, which I installed in my own cover. Nothing is ever easy Ron

email (option): ronpier@talk21.com