N 5166 is 1924. According to the 1924 Evinrude catalog: the tank should be brass the same as a 1923, the carb should be a Zenith with float feed, when the motor is running and you lift the tiller arm the lower unit should swing around and go into reverse mode, lifting the tiller arm only halfway should lock the tilting ability for starting purposes, the gearcase has 3 ball bearings and a stainless steel prop shaft, there should be a drain valve at the bottom of the cylinder water lines where they enter the tower assy.
Your 2 tilt adjusting arms have been cut off. The original tiller and its mechanism is missing. The brass tank and ID tag is missing. This motor is a good candidate for fixing and running as-is. It has character.