'63 Wildcat factory 4-speed with the dual-quad Super Wildcat 465. With only 9,979 miles

according to the Buick owners’ community, only thirty four-speeds were installed in a Wildcat—broken down as eighteen four-door hardtops, six coupes, and six convertibles.

Buick didn’t advertise this combo for 1963, but a select few had enough clout with Buick brass to get one. It was the muscle car for the middle-aged executive who secretly wanted to drag race on the weekends.

https://www.autoevolution.com/news/1-of-1-dual-quad-1963-buick-super-wildcat-4-door-4-speed-emerges-it-s-absolute-eye-candy-255487.html#

I never heard of the Gran Sport trim level of the 66 Super Wildcat

According to The Standard Catalog of American Cars 1946-1975, only 22 1966 Wildcat GSs were of Super Wildcat specification.

https://www.hotcars.com/rarest-buick-ever-made-beastly-60s-muscle-car/

Buick Wildcat, had one of the best designed symbols, and rarely seen

http://en.wikipedia.org/wiki/Buick_Wildcat
Interestingly, engine names referred to engine torque output rather than engine displacement. The "Wildcat 445" was a 401 CID V8 that produced a peak torque rating of 445 ft·lbf (603 N·m), while the "Wildcat 465" was a 425 CID V8 that produced 465-FT-LB of torque. The "dual quad" version of the Wildcat 465 was dubbed "Super Wildcat."
There was a guy in San Diego who took a dual quad 455 out of a Wildcat and stuffed it into his 71 Dodge Charger. When I asked him "Why?!" He responded that he was a tinkerer. aka goofball who had too much time on his hands, a rare engine, and a need for extra attention. You know the type.