Not always framenumbers are being changed to build a WD M20, sometimes people have f.e. already old papers laying around and find it cheaper to change a framenumber to match it with the papers. The frame is indeed in a scruffy state, but why is the exact location of the framenumber painted in a more recent yellow?
I have had this frame in my hands last weekend, took all the time to inspect it closely I came to the conclusion that this is very likely a later post war frame with a 'WM' frame number. It is well possible that this is a replacement frame, with a later added number, like Rick mentioned.
I concurr with Bastians assessment...I also examined this frame closely for a friend who was interested in buying it...We ended up walking away...Irrespective of whether it was 'right' or not (and I thought it wasn't) it would never fit in with peoples expectations of 'normal practice' so would always have its provenance questioned...From the dimensions I'd say the extra bracket was probably added for the head steady of an OHV engine that came from a swinging arm frame...Ian
