Wiper speed?

I have a 71 Duster and my wipers aren’t working, I’m getting power to the switch, but not the wipers, I was reading that 71 dusters came with 3 speed wipers, so before I drop the money on a nos switch I need to figure out if I have a 2 speed or 3 speed. I can push the knob in and click it twice to the right, I would assume that means that I have 2 speed wipers, but I want to make sure as both switches look the same to me. Thanks