This time the pin fell out when one bolt in the clevis hitch fell out and then two of them broke (we had the local welding shop change the front to a single draw bar on the spreader from the usual split hitch. So now we use the tractors 3" pin to hold it and now we found out other weaknessess.) We will now put a bolt in the bottom of that big pin (didn't think it needed it when the tractors pull augerwagons fine.  Other times the hitch pin has broken from all of the constant hitting of the pin when going through the field. Those times the safety chains held.

I am also thinking if one of those screw type log chain links would work better then the hooks.