Hi Floyd, I have a silly question for you. I recently picked up a used plane with a four stroke motor in it. Its my first four stroke so please forgive my ignorance. The motor is a .91 with a pump and regulator. I looked up the manual and in there it mentions an "O.S. Safety Locknut Assembly." The diagram isn't very clear but it just looks like a jam nut. Would the motor have come with it new or would that have been an aftermarket item? Can I use any old nut or does it need to be of a particular hardness like the original equipment stuff? Do I really need it? What do you suggest?