This transitional model has both elements of 1c and 1d, more of 1c but with serial # in 1d range.
FED 1c:
Produced: 1937-1939
Engravings on camera top are the same as on the Fed (1b) camera. Shutter speeds are identical to predecessor‘s as well. The only visible difference from Fed (1b) is changed roudness form of housing. The particular changes were influented by complicated construction of the new conceptional camera Fed-B. These cameras came with slow speeds knob on the camera's frontplate (Leica III).
Serial number range: # 55.000 to # 92.000/95.000 [2].
Known serial numbers:
115347 - Vladislav Kern