I just picked up this hub on a late 70's bike. I wonder if this is a 2 speed or 3 speed. It had the chain like a SA, but the shifter on the handlebars is smaller than a SA and doesn't have notches for each gear and I don't see any numbers, just the word "torpedo". From what I've looked at , all the 2 speeds were automatic, so this should be a 3 speed?