Manning, Maxwell, & Moore
Engine Gage Unit for US Army Air Force Fighters, 1942, Type B-7, AN-5774-B
The US Army Type B-7 Engine Gage Unit was used across a variety of aircraft of the US Army Air Force during WWII. In particular, the B-7 made by Manning, Maxwell, and Moore part number 6548-73-15 was used in fighters P-38 Lightning, P-39 Airacobra, P-40 Warhawk, P-47 Thunderbolt, and P-51 Mustang, according to the US Army Air Force's Maintenance Interchangeability Cross Reference Chart dated Dec1943. This example is marked AF USARMY on its face and had a serial number prefix of AF-42, evidence of a manufacturing year of 1942.
The B-7 Engine Gage Unit displayed 3 metrics with one instrument: Oil temperature (from 0-100 deg C), Oil pressure (from 0-200 PSI), and Fuel pressure (from 0-25 PSI). See spec sheet in photo gallery. The Type B-7 eventually became designated the AN-5774-B when the Army/Navy designation system was introduced during WWII. The oil temperature was measured via capillary tube (not included) and the pressures were measured via bourdon tubes.
It is in good condition given its age. The capillary tube has been removed. The dial markings and paint on the pointers have aged, and the glass and case are intact. Measures 3.25 inches diameter and ~2.75 inches deep. Not too bad for a 70+ yr old artifact. See photos.