My experience with the early Addco bars is that they were poorly designed. The width was way off causing the end links to constantly be stressed and eventually bend. Helwig makes a much better one.
So, here’s the sway bars and all their related bracketry. Not sure who made them, but they’re as old school as all get out. There’s some rubber strips that go around the axle housing to cushion the brackets and give ‘em some gripping power.