He said that a grade 8 bolt isn't as strong as a 5/8" hitch pin. Etrailer.com says that a grade 8 bolt has a shear strength of 90k, the same as a 5/8 hitch pin. However, it's harder and more likely to break as it won't flex like a real hitch pin. It will also be more likely to egg out the pin hole in the hitch.
