I just received a pre WWII 6x9 cm Welta Weltur from Jurgen Kreckel certo6. So far I have not found a serial number on the body. The link to the serial number listing you gave helped me date the Compur Rapid shutter as early 1939 and Carl Zeiss Jena f4.5 uncoated Tessar as late 1937. The lens must have sat in someone’s inventory for a while until the rest of the camera was put together just before Blitz Krieg started. Thanks for helping identify an approximate build date.