The chainguard fixing on the back of the case is at a different angle due to the different frame....Try checking the post war (46/47) inner chaincase number for rigid B Models to see if that is the same as they used essentially the same rear frame section...Ian
Rob a correction to your probable typo. The WB30 inner chaincase is 65-7578 and is listed in the 1947 parts list as being also fitted to the B31-32-33-34. Ron
Rob a correction to your probable typo. The WB30 inner chaincase is 65-7578 and is listed in the 1947 parts list as being also fitted to the B31-32-33-34. Ron
PS I've found the number on the outer 66-7503 which seems to be the usual BSA way on being one number out (66-7502). I guess for a part before it is finished?