It is a Model 15. Although I don't know what - model it would be. What I do know is that it is a treadle machine that was converted to electric and someone jury rigged the wiring. If it was wired in the most common way it would have a plug on the end of the wire from the motor, and a cord block. However some one hard wired it so it would have just the wires from the motor to the power cord and probably the foot controller.
That Delco motor is a good motor if not worn out, so I'd check it and rewire it as I said above. I'd also put a light on it.
Or, I'd put it back in a treadle cabinet if I had one.
Joe