Heres some pics of my airfer swing arm. As you can see they are a one piece design and unwelded. Hollow in construction with a nylon insert through the centre which SHOULD give immense strength. God knows why it should break where it did. Just one other thing, original pic shows non factory welding on frame so who knows, may have suffered damage previously which resulted in fracture of arm. Also, agree with others, billet would be best but nothing is unbreakable. Nick