1968 Buick GS400 Convertible | 455 V8, 4-Speed, Classic Muscle in PA

Route 61 Classics in Pennsylvania is proud to offer this 1968 Buick GS400 Convertible for sale, a striking muscle-era convertible that combines timeless styling with professionally built Buick big-block performance. Finished in Scarlet Red with a black power convertible top and black interior, this GS400 presents beautifully and commands attention wherever it goes.

Under the hood is a 455ci Buick V8, using a correctly disclosed 1970–71 Buick block (casting 1238861). The engine was professionally built with performance and reliability in mind, featuring TA Performance Stage 1 Street Eliminator aluminum heads, Wiseco .040-over forged pistons, ARP fasteners, MLS head gaskets, upgraded valvetrain components, and a performance camshaft. Induction is handled by an aluminum intake manifold topped with a Holley 750 CFM vacuum-secondary carburetor (LIST-3310-3), while ignition duties are managed by an MSD distributor.

This combination produces a dyno-verified 428 horsepower and 468 lb-ft of torque, with documentation included — delivering strong street manners, massive torque, and the unmistakable sound Buick big-blocks are known for. Cooling is handled by an aluminum radiator with dual electric fans, and exhaust exits through TA Performance headers feeding a deep-sounding dual exhaust system.

Power is sent through a Muncie 4-speed manual transmission to a Buick-specific 8.2” BOP 10-bolt rear axle, preserving the authentic muscle-era driving experience. The suspension remains true to its GM A-body roots, complemented by factory power front disc brakes for confident stopping.

This GS400 comes with a binder of receipts and documentation, along with an extensive trophy history from shows and events — a clear reflection of the quality of the build and the pride of ownership. The undercarriage is clean and solid, and the car runs strong, drives well, and presents as a true enthusiast-owned example.

If you're searching for a 1968 Buick GS400 Convertible with a 455 V8, 4-speed manual, documented performance, and show-quality presence, this is a standout opportunity. Available now from Route 61 Classics in Orwigsburg, Pennsylvania.