Pontiac Bonneville 421 SD
The Pontiac Bonneville 421 Super Duty represents the peak of early 1960s full-size performance. Under the guidance of Pontiac chief engineer John DeLorean, the Super Duty program produced factory race cars that happened to be street legal. The 421 Super Duty engine featured forged internals, aggressive camshaft, dual four-barrel carburetors, and exhaust headers — producing a conservatively rated 405 horsepower. These cars dominated drag racing and stock car competition, embarrassing competitors with smaller engines. Only a handful of 421 SD Bonnevilles were built, making them among the rarest and most valuable Pontiacs. The Super Duty program was GM's most aggressive factory racing effort until corporate management banned all racing involvement in 1963.
Genuine Super Duty cars are extremely rare and expensive — verify through PHS documentation. Most 421 SDs went into Catalinas (lighter). Bonneville SD versions are the rarest. The investment potential is excellent. Standard Bonnevilles from this era are much more affordable and still desirable full-size cruisers.
Super Duty production was extremely limited. The 421 SD engine was hand-built by Pontiac's performance division. GM's corporate racing ban in early 1963 ended the program. Only about 88 Super Duty 421 Catalinas were built; Bonneville versions are even rarer.