I figured they were the same part except for the mounts. If he is trying to keep it somewhat stock as he originally mentioned because it is a 383S car. He mentioned just wanting the borgeson box and mentioned his dented K frame before seeing the QA1 K. I'd recommend to just make a 67 Slanty K into a big block one, this way it kinda keeps its pedigree or a 68-72 one into a big block one for the better idler arm mount.