70 dart turn signal cam question, what the heck?

'70 turn signal switches are one-year-only, and they're not available as aftermarket parts. The '71-up switch works in a '70 car, but has a differently-shaped hazard flasher knob. If you're talking about a smaller cam on your old switch, that sounds more like a '69-down switch. Oldkimmer's got the right idea: please post pics.

Maybe before that, though: is this "Hey, that part is shaped differently!"? Or is it "Hey, the turn signals don't self-cancel with this switch installed because that part is shaped differently!"?