I have a 1929 Singer No.66 serial #Y7506668, in very good condition. I believe this machine may have been place on a Singer pedal base from another machine at some point. This machine is electric - it came with an electrical cord but it is not currently attached. The base is also in excellent condition and all components for the pedal still operate smoothly. I do have photos that I will upload.

I'm not sure how to measure this.