Wow, that's the "console gear selector" I remember. What's kinda spooky is that the sissy bar very-closely resembles the replacement I had. The replacement I had was shorter than the too-tall original, and had the slight backwards tip (just like the posted photo). Maybe that's all the bike shops had for replacement sissy bars in 1966. My bike didn't have a black seat (it was white, I believe). Other than the seat color, that's so dang close. Find a replacement rear fender, and that'd be a nice bike cleaned up... at least oil the rusty chain (sorry, my OCD is talking to me). Thanks for posting that!
Gotta wonder: why are so few of those shifters seen? Was that shifter short lived? Were there issues with it? I never had any trouble with mine. If I had to guess (as someone retired from the manufacturing sector), that shifter was probably pricey to make, and the one with the round body (as seen from the side) was likely readily available off-the-shelf from a bike-parts maker. Too bad because that's a good-looking shifter, and it resembles what some of the cars with console shifts had back then.