Your "car guy" is exactly right, Wes. I had to zoom way in to see what you are talking about, but Pat's photo does show nuts that are too tall in my opinion.
Nyloc nuts have a nylon insert that is supposed to deform and grip the threads to keep the nut from coming loose with vibration, etc. But the last thread at the tip of the fulcrum pin is not full diameter and so may not deform the nylon enough to get a good grip. You need a nut that lets at least part of the thread protrude beyond the nut, otherwise it may come loose in service and fall off.
One easy solution is to clean the threads with solvent and use a drop of Loctite.