Early old General Motors combination ammeter (current) and water temperature gauge. We're not sure of the exact vintage or model this fits, but are guessing it's from the late 1920 or 1930s from the gage face and mounting. Maybe as late as the 1940s. Great for your hot rod restoration project.
The temperature gauge is marked for "Alcohol Boils" within the "Normal" range. It is marked on the back "AC - Made in USA" and measures about 3 13/16" long and 3 5/8" over the mounting ears. The face is 2 3/16" across.
We don't know much about this and haven't tested it. We are selling it AS IS for restoration or parts.