I was looking for several 5/8 inch stop nuts but could not find them at my local hardware stores or big box stores. All I could find locally was 1/2 or 3/4. These were priced about the same as the store and the shipping with reasonable considering driving out 10 bucks worth of gas and still not finding them. I’d rather pay less than that for shipping and just let them come to my door. Very high-quality too by the way!!
I changed my setup from a castle nut to nylon lock nut. There was too much slop with the castle/cotter pin. I will be testing it soon in the field.