Hi Lex,
now this is very interesting reading - we found the missing linking number ; 😃
No sidecar lug on the front frame downtube - tank mountings played V shape - 41/G3L specification...albeit with a "wrong" number.
The bike is in Luxembourg, left behind by retreating german forces in september 1944. The owner family laid their hands on it, got some petrol from liberating US troops...and had some fun before the germans saying hello again in december. 1944.
My guess is then a MAJOR rebuilt during the war...before being captured by the germans.
...the (radio) connections in Normandy 1944 weren't always good either...
best regards.
Claude