How too mount the alt brackets to the exhaust

[67gmcstepside]

Just received these from southern parts from his parted 68 V8. I can't figure out how the angled bracket mounts to the exhaust thread boss's. It just doesn't seem to fit in any why I try. I assumed 67/68 were the same and mounted the same. Most pics I find the alt is covereing up the lower bracket. Any insight would be apprecated. Many I have the wrong ones but Southern did say they mounted to the exhaust :-( I know I will feel stupid if they really do fit and I just couldn't figure it out.