Rebuilding some farm implements and have a BOLT PROBLEM There is a guy at the community farmers market that said good luck finding the bolt and nut that the arrow is pointing to. Before I toss this into my rust removal tank (that works great) I want to make sure I could at least find one of the nut and bolt. Its square head and its square under the head and the chain bridle has a square hole in it the other side has just a washer and nut no big deal. The safety chain bridle and bolt move as one. After a 100 years of rust I didn't want to chance just twisting it off. Im going to rust tank it and try it again one of the other like this came off by hand after the tank treatment. What are these bolts called? Anyone know? So I can call around and ask without sounding like someone that knows nothing about it. Well I dont but dont want to. 
