In 1967 Plymouth introduced the GTX as an optional package on the Belvedere model line. The GTX was a two-door vehicle that could be purchased in either convertible or hardtop configuration. It had all the performance options pre-installed and packaged in a stylish vehicle design. The excellent handling was courteous of the leaf springs, modified shocks, ball joints, and torsion bars. Under the hood was a 440 cubic-inch eight-cylinder engine, dubbed the Super Commando 440, producing an astonishing 375 horsepower. A 426 cubic-inch Hemi engine was optional and boosted horsepower to 425. It cost just a little over $540 for the Hemi engine and only 720 buyers purchased this option. The three-speed automatic transmission was standard but a four-speed manual could be purchased to replace the automatic gearbox.
Plymouth offered a Super Stock R023 version that included the Hemi engine and was intended for the drag strip racing circuit. To reduce weight, all non-essential items were removed including the heater, radio, and carpet. Only 55 examples were produced. The 440 was a tunable engine, still able to be driven on the street, and was not plagued with the same tire-spin that the Hemi endured.
In 1968 the GTX was modified both aesthetically and mechanically. The taillights and grill were revised and a new hood design was used in place of the former design. In the front were disc brakes. The suspension was modified, the tires became wider, and it now featured a limited-slip differential. It shared many of the same mechanics as the Plymouth Road Runner, an economical, performance machine. The TorqueFlite automatic gearbox was standard but could be replaced with a four-speed manual at no-cost. Only 450 GTX's were ordered with the Hemi option, costing them $564 over the base $3355 price.
For 1969, the GTX was modified only slightly with most of the changes to the grille and taillights. The big news was the Hurst shifter, Air Grabber option, and various rear axles. There were now three engine options. The 440 cubic-inch engine's single four-barrel carburetors was replaced with a three two-barrel carburetor resulting in 390 horsepower. It was dubbed the 440+6 and cost just $120 over the base 440 cubic-inch engine that produced 375 horsepower. Only 209 buyers shelled out the $700 for the Hemi engine. This was the final year the convertible option was offered.
In 1970 the GTX was restyled and given a hood scoop that did nothing but add to the aggressive look of the car. A bulge in the hood completed the look of the vehicle. The 440 cubic-inch 8-cylinder engine was standard. The 440+6 and 426 Hemi were optional. The 440+6 was a popular option with 768 buyers opting for the performance increase. Only 72 buyers purchased the Hemi. Sales were slow for the GTX in 1970 with only 7,748 examples being produced. The Road Runner was partially responsible. It was a lost-cost alternative that was faster than the GTX. Plymouth decided to produce the GTX in 1971 but it was the final year. The styling was updated, its lines were curvy and it sat atop a shortened wheelbase. To improve the handling, the GTX received a wider track. The Air Grabber was optional. The 440 cubic-inch engine was standard, now producing five less horsepower than the private year. 30 examples of the Hemi were ordered. The 440+6, still available, produced 390 horsepower. With only 2,942 examples sold, Plymouth decided to make the GTX as an option on the Road Runner for 1972. By Daniel Vaughan | Jun 2007