Plymouth GTX 440+6

Plymouth GTX 440+6

The Plymouth GTX was introduced for 1967 as Plymouth's premium muscle car, positioned above the budget-oriented Road Runner and below the ultra-expensive Hemi cars. The GTX came standard with the 440 cubic inch Super Commando V8, making it the only intermediate muscle car of the era to include a big-block engine as base equipment. This positioning gave the GTX a unique character: it was a gentleman's muscle car that combined serious performance with a level of refinement and standard equipment that separated it from the stripped-down Road Runner.

The 440+6 (also known as the 440 Six Pack) was the ultimate expression of the GTX, featuring three Holley two-barrel carburetors on an aluminum Edelbrock intake manifold. The factory rating of 390 horsepower and 490 lb-ft of torque was conservative; the Six Pack setup was known to produce significantly more power in real-world conditions. The progressive carburetor linkage meant the center carburetor handled normal driving, with the two outboard units opening under heavy throttle to provide a massive surge of additional power.

The Six Pack system provided one of the most dramatic driving experiences of the muscle car era. At part throttle, the single center carburetor made the GTX docile and manageable. But when the throttle was floored, the progressive linkage opened all three carburetors with an intake howl that was unforgettable, and the engine's character transformed from refined cruiser to pavement-shredding monster. Period road tests consistently recorded quarter-mile times in the mid-13-second range, making the Six Pack GTX one of the quickest cars of the era.

The GTX came with a comprehensive list of standard equipment that justified its premium price. Bucket seats, center console, Rallye instrument cluster with 150-mph speedometer and tachometer, front disc brakes, heavy-duty suspension, and chrome exhaust tips were all included. The exterior featured distinctive GTX badging, stripe packages, and premium trim that set it apart from lesser B-body Plymouths.

The 1970 model year saw the GTX receive the new B-body styling that also underpinned the Road Runner and Satellite. The 1971 model, riding on an even larger B-body platform, was the final high-performance GTX before emissions regulations and insurance costs killed the muscle car era. The 1971 GTX with the 440+6 is particularly desirable today, representing the last of the true high-compression, high-performance muscle cars before everything was detuned for 1972.

Total production of Six Pack GTXs was limited, with approximately 2,035 built across the 1970-1971 model years. This relative rarity, combined with the car's premium positioning and devastating performance, has made the 440+6 GTX one of the most collectible non-Hemi Mopars. Four-speed manual cars are significantly rarer and more valuable than automatics, though the bulletproof TorqueFlite automatic is the preferred transmission for many enthusiasts.