Engine Gauge Unit (Triple), AN5774-8 C-121 These cameras were designed to

These cameras were designed to record results obtained in aerial and ground gunnery training and for producing visual records of aerial combat

see illustration from the B-17G Erection and Maintenance Manual in the photos

The Special Devices Section grew and became the Special Devices Division

The AN-104 is designed for 100 to 156 MHz

Engine Gauge Unit (Triple), AN5774-8 C-121 These cameras were designed toThe WWII era Engine Gauge Unit (aka Triple Gauge), AN5774 8, displayed the performance of 3 engine parameters in one instrument: Oil Temperature, Oil Pressure, and Fuel Pressure. The AN5774 8 unit was used in the US Army Air Force fighters P 38E Lightning, P 40 Warhawk, P 47 Thunderbolt, and P 51 Mustang according to their Maintenance Interchangeability Chart dated Feb 1945, as well as having been used in other military aircraft post war. This