Out of three here, two are '39 models. The 20" frame was not produced after the war from what I have seen in the serial numbers I have in the spreadsheet, so Wartime and Prewar is what the numbers are telling me. Always looking for more examples and I am NOT an expert, just a student on this - now stuck in perpetuity and doomed to remain in this class!!
If you have one of these, please send me the serial number, and a photo of the full drive side, the serial number, and any other information you may have to offer.
Thanks,
REC