This is from a friends AC 720. I am puzzled by the clutch anti-rotation method used(it's half-assed to say the least). However, I've seen the same set up in AC parts illustration,so it's the intended method.If the master link pin diameter matched the holes ,I wouldn't question the design,but I've never seen a m/link like that. Perhaps someone with AC/Simplicity experience can comment. This is the rear PTO unit.