I drove one like that for a few weeks back in '73 or 74- I think it was a '62, and an H model. My only exposure to the duplex trans. Holy cow... It was a single drive, and I remember it as riding quite nicely and being really solid. The engine had a confident sound to it- like "I'm going to outlast you, buddy". It did- but only because of the trans.
Anyway, there's an H model sitting down by pottstown (it's the exact same color, even!). It's parked by the road, as if it might be for sale. It's a screw.