Gyro Horizon Indicator, AN-5736-1, Sperry 656768
Here is WWII-era vacuum-driven Gyro Horizon Indicator Type AN-5736-1. According to the Maintenance Interchangeability Cross Reference Charts of the Air Forces US Army dated Dec 1943, this Gyro Horizon was ubiquitous in its use, appearing in bombers B-17, B-24, B-25 and others, as well as fighters P-38, P-40, P-47, and P-51.
The knobs function. The center knob adjusts the indexing indicator for the view angle of the pilot. The caging knob pulls out and turns to cage the gyro as it should. The instrument looks terrific and would make a wonderful display piece.