Oil Quantity Indicator, C-54, R5D, Douglas Skymaster, Bendix 6007-58A
Here is an Oil Quantity Indicator, Bendix part number 6007-58A-15-B, as illustrated on in the US Army Air Force's Flight Manual, dated January 1945, for the Douglas C-54 Skymaster Transport (see photo). Appearing on the co-pilots panel, it is marked for engines 1 &2. Measures 3.25in diameter and ~6in deep. The scale contains markings in the US Navy style color Munsell Green, so it may have been used in the USN's R5D transport.
It is in nice condition given its age. The dial markings are clear and the glass and case are intact. See photos.