B31 Gearbox question

[sidewaysid]

Hi
Would there be anyone in the know who is able to tell me...would the internals of a 1940s B31 box fit into a casing from a 1938 bike, physically to main casing is the same, lugs to frame plates all match up. The casing number on the 1938 box which I have is 65-3394 and the casing from a 1949 B31 seems to be 66-3141. I am sure the speedo drive is different, but I have no idea if all the other parts from a later box go into the casing...any advice .

Cheers

Phil

[JulianS]

The B box changed for 1949 to same as the M box. You would need to go through the parts books and check all the numbers.