Plymouth’s 1970 GTX was already losing sales to its cheaper Road Runner sibling, and the rare 440 Six Barrel option most collectors chase today made up only a small fraction of that shrinking total. With just 7,748 GTXs built that year and roughly 678 carrying the triple-carb 440, the math behind this car’s rarity is stark.
The luxurious GTX sales were down because of the budget priced Roadrunner, which sports similar lines and has many of the same power options available as well. There was no convertible GTX on the order sheet in 1970, but the “Grabber” hood option is back although now revised, with only one opening and it’s located centrally on the newly added “power bulge” hood. The basic engine is the 440 with a four barrel carburetor or the next step up is the 440 six pack and then the 426 Hemi is a little more tempting option.
As an Amazon Associate I earn from qualifying purchases.
MCF thanks Gateway Classic Cars for the images provided here
By 1970, Plymouth’s original muscle flagship had a problem: its own cheaper sibling was outselling it. The Road Runner offered nearly the same performance for less money, and GTX buyers had shrunk to a small, serious crowd willing to pay more for standard equipment most competitors charged extra for. That crowd got smaller still if they wanted the top engine option, one so rare that most GTX buyers never even ordered it. The production numbers behind that engine explain exactly why surviving examples command the attention they do today.
The Engine Most GTX Buyers Never Chose
Above the standard 440-cubic-inch four-barrel, Plymouth offered the 440 Six Barrel — a big-block RB engine fed by three two-barrel carburetors, a 350-cfm unit in the center flanked by two 500-cfm carbs, rated at 390 horsepower at 4,700 rpm. It sat below only the 426 Hemi in Plymouth’s 1970 performance hierarchy, and it came bundled with heavy-duty everything: shocks, suspension, driveshaft, U-joints, rear axle, brakes, and a wider six-inch wheel, plus standard bucket seats.
How Rare Is Rare? The 1970 Production Numbers
Total GTX production for 1970 fell to just 7,748 cars, with the standard 440 four-barrel accounting for roughly 6,400 of them. The 440 Six Barrel option was ordered on a small fraction of the total — commonly cited around 678 cars — and the 426 Hemi rarer still, at only 72 units. That scarcity is a big part of why a well-documented, numbers-matching Six Barrel or Hemi GTX from this year draws serious money at auction today. The scarcity is not just a collector talking point, either: some original buyers held onto their cars for decades, and one Vietnam veteran who bought his 440 Six Barrel GTX new in 1970 was reportedly still driving that same survivor 55 years later.
Born as Plymouth’s ‘Gentleman’s Muscle Car’
When Plymouth introduced the GTX for 1967, the idea was to build a muscle car with genuine road manners and standard heavy-duty equipment rather than a stripped-down budget racer, a positioning that set it apart from more spartan competitors from the very beginning. Standard equipment like the heavy-duty suspension, dual exhaust, and a big-block V8 as the only available engine choice reflected that philosophy, aiming at buyers who wanted serious performance without sacrificing comfort or refinement on the way to the drag strip.
The Road Runner Changed Everything
Plymouth launched the Road Runner for 1968 on the same basic B-body platform as the GTX, but stripped down and priced dramatically lower, deliberately targeting buyers who wanted big-block performance without paying for the GTX’s standard comfort and convenience features. The Road Runner’s runaway sales success directly explains the GTX’s declining numbers by 1970, since a buyer chasing straight-line performance on a budget increasingly had little reason to pay extra for the GTX’s additional standard equipment when a Road Runner could be optioned with nearly the same engines for less money.
The Grabber Hood, Explained
The “Power Bulge” hood mentioned on this car’s original listing, along with the “Grabber” hood option, refers to a functional or semi-functional scoop treatment Plymouth revised for 1970, consolidating what had been a twin-opening design into a single centrally located intake. It’s a small but telling detail of how Plymouth kept updating the GTX’s appearance year to year even as the model’s sales continued sliding, treating styling refinement as a way to keep the car visually current even without a full redesign.
Reading the Factory Wheel and Trim Details
Cars like the one pictured here typically wore Rallye-style wheels along with the GTX’s signature dual body-side stripes running the length of the car and “GTX” badging on the front fenders and grille, styling cues Plymouth used specifically to separate the GTX visually from both the cheaper Road Runner and the standard Belvedere-based Satellite it was built alongside. Details like these matter enormously to collectors today, since GTX-specific trim pieces have become increasingly difficult to source as fewer surviving cars retain their original hardware.
How the GTX Name Eventually Disappeared
Plymouth discontinued the GTX as a standalone model after the 1971 model year, folding what remained of its identity into an option package on the Road Runner for 1972 before dropping the name entirely soon after as the muscle car era wound down under rising insurance costs and tightening emissions regulations. That makes the 1970 model year featured here one of the GTX’s final seasons as a genuinely distinct model, built during a period when the whole muscle car segment was already beginning to contract even before most buyers realized it.
Why Insurance Costs Reshaped This Whole Segment
Rising insurance premiums on high-horsepower muscle cars hit models like the GTX especially hard by the start of the 1970s, since insurers increasingly based rates on engine displacement and horsepower ratings rather than a car’s actual trim level or intended buyer. A car marketed toward comfort-seeking performance buyers, like the GTX, found itself penalized by the same underwriting formulas applied to stripped-down budget muscle cars, undercutting exactly the demographic Plymouth had originally built the model to attract.
What Makes a 440 Six Barrel Worth Finding Today
Beyond its rarity, the 440 Six Barrel’s triple-carburetor setup represents a specific, relatively brief window in Mopar engineering when multi-carburetor induction was considered a viable middle ground between a standard four-barrel and the far more expensive, harder-to-service 426 Hemi. Collectors specifically seeking out 440 Six Barrel cars today are drawn to that engineering compromise as much as the performance numbers themselves, since it represents a genuinely different approach to making power rather than simply a smaller-displacement alternative to the Hemi.
Share your thoughts in the comments below.
Republished by Blog Post Promoter
Related posts:
Dodge Coronet 1969 images
Chevrolet Impala 1967 images
Pontiac Trans Am 1978 images
Chevrolet Chevelle SS 1969 tribute images
Dodge Challenger SRT8 2008 images
Chevrolet Corvette 1973 images
Lincoln Continental Mark IV 1959 images
Buick Special 1956 images
AC Cobra carbon fiber replica images
Chevrolet Camaro SS 1969 images
