The brackets were not welded originally (riveted), not a great idea for strength and durability over the long-term I would guess. Here is what a 3/4-ton leaf attachment points should look like. Let me know if you want detail pictures of overload springs on a 54' as I have a spare 3600 frame with that installation (none of those brackets weld either).
https://www.flickr.com/photos/advance-design_parts_co/8129054429/in/set-72157631867396207