In 1966 a one-year-only Wildcat “Gran Sport Performance Group” package could be ordered by selecting the “A8/Y48” option. Two engine choices were available. The single carb 425 CID/340 hp V8 was included in the base package price but a 360 hp (268 kW) dual-carb set-up was also available at extra cost. Initially, this 20 hp (15 kW) upgrade remained a dealer installed carb/intake modification bolted to stock MT-coded engines but eventually these “Super Wildcats” could also be obtained direct from the factory with MZ-coded engines. Rounding out both the base and Super GS packages were dual exhaust, heavy-duty suspension, posi-traction and updated rear quarter-panel “GS” badging in the new, initials-only format employed on all post-1965 Gran Sports. A total of 1244 Wildcat GS’s were built by Buick during the model year. Of those 242 were convertibles and the rest were hardtops. A mere 22 (consisting of an unknown mix of both body styles) earned Super Wildcat decals.