Serial number range: 166001-566500 (1933-1941, approx. 4,500 produced). Production by year: 1933: #166001-167000 (1,000 units); 1934: #235001-236000 (1,000 units); 1937: #377001-377500 (500 units); 1938: #437001-438000 (1,000 units); 1939: #538001-538500 (500 units); 1941: #566001-566500 (500 units).