Manifold Pressure, Dual, Set for 4-Engine Aircraft, AN5770-2, D-11
Here is a set of WWII-era AN5770-2 (formerly D-11) Dual Manifold Pressure Indicators, as used in four-engine of the US Army Air Force such as bombers B-17, B-24, and B-29 and transport C-54. The indicator marked for engines 1 & 2 was made by Ranco with a 1943 manufacturing serial number prefix. The indicator marked for engines 3 & 4 was made by American Meter with a 1944 manufacturing serial number prefix. These were also used in twin engine aircraft of the US Army Air Force such as B-25, B-26, and C-47, but with markings for engines 1 & 2 or L & R.
These indicators are in good shape given their ages. The lettering is precise, the glass is clear and case intact. Both have operating ranges painted on the glass for the last aircraft in which they were installed. Measure 3.25 inches diameter and 3 inches deep.