The original Plymouth Duster was a Valiant-based A-body fastback coupe sold for model years 1970–1976; it is best understood as one generation, not several. Its engine range ran from Slant Sixes to the performance 340 and later 360 V-8, while packages such as Twister, Gold Duster, Space Duster, and Feather Duster served different purposes. A Duster’s value depends on its exact year and configuration, condition, originality, and documentation—not on one generation-wide price.
Which Plymouth Duster does this guide cover?
This guide covers the original two-door fastback Duster introduced for 1970 and discontinued after 1976. Plymouth based it on the Valiant platform and structure, but gave it distinctive exterior styling and a fastback roofline. For 1971, Plymouth dropped “Valiant” from Duster badging. Later vehicles reused the Duster name, but they are outside the scope of this original model guide.
Hagerty’s history says more than 1.3 million original Dusters were sold. Separately, Hagerty’s 2025 model-history report gives 217,192 Valiant Duster Coupes sold in 1970. These figures describe historical production or sales, not present-day values.
Plymouth Duster engines and performance
The 1970 Duster engine range included two Slant Sixes and two V-8s. Exact output depends on model year and rating method; early gross horsepower figures should not be compared directly with later SAE net ratings.
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| Engine | Verified context | What to know |
|---|---|---|
| 198-cubic-inch Slant Six | Offered in 1970; Hagerty gives 125 hp for the small Slant Six. | Part of the original economy-oriented six-cylinder range. |
| 225-cubic-inch Slant Six | Offered in 1970 and used in the Feather Duster package introduced for 1975. | The Feather Duster paired this engine with lightweight aluminum components. |
| 318-cubic-inch V-8 | Offered in 1970. | A V-8 choice in the original lineup; consult year-specific literature for exact output and equipment. |
| 340-cubic-inch V-8 | The 1970 high-performance engine was rated at 275 hp in Hagerty’s historical overview. For 1972, Hagerty gives a 240-hp rating. | The 1972 figure reflects the shift to SAE net ratings and lower compression; it is not directly comparable to the earlier gross rating. |
| 360-cubic-inch V-8 | Replaced the 340 for 1974. Hagerty gives the 1976 Duster 360 a 220-hp rating. | Use exact-year factory literature for details beyond these verified historical figures. |
Hagerty describes the 340 configuration with a four-barrel carburetor, three-speed manual transmission, heavy-duty suspension, and front disc brakes. Equipment could vary, so check the exact car’s year-specific documentation rather than assuming every Duster 340 had identical specifications. The available research does not establish a complete year-by-year matrix of engines, transmissions, and outputs.
Trim and package guide
| Package or model | Purpose | Verified details |
|---|---|---|
| Duster 340 | Performance model | Centered on the 340 V-8 and supporting performance equipment. Documentation is important because lower-powered Dusters have been converted. |
| Gold Duster | Appearance package | Hagerty dates its first appearance to 1970. Treat it as an appearance special, not a separate engine family. |
| Twister | Appearance package | Introduced in 1971. Hagerty describes 1971 cues including Rallye wheels, side stripes, sharktooth grille, flat-black hood with scoops, and bucket seats. The 1972 version lost the special hood and grille treatment described for the prior year. |
| Space Duster | Utility-oriented package | Added for 1973, with a folding rear seat and carpeted trunk to increase cargo utility. |
| Feather Duster | Weight-saving, economy-oriented package | Added for 1975 with the 225 Slant Six and lightweight aluminum components. Hagerty quotes period advertised economy ratings of 24 mpg city and 36 mpg highway; these are historical ratings, not modern or independently tested results. |
Model-year changes to recognize
| Model year | Changes supported by the research |
|---|---|
| 1970 | First model year. The lineup included 198- and 225-cubic-inch Slant Sixes and 318- and 340-cubic-inch V-8s. Gold Duster also appeared in 1970, according to Hagerty. |
| 1971 | “Valiant” was dropped from Duster badging. The sharktooth grille and Twister package arrived. |
| 1972 | Compression was lowered and SAE net ratings adopted; Hagerty gives the Duster 340 a 240-hp rating. The Twister lost the special hood and grille treatment described for 1971. |
| 1973 | The front end and taillights changed, and federal bumper requirements brought larger bumpers. The Space Duster package joined the lineup. |
| 1974 | The 360 V-8 replaced the 340. |
| 1975 | The grille was restyled, and the Feather Duster package appeared. |
| 1976 | Final model year for the original Duster. Hagerty’s historical overview gives the Duster 360 a 220-hp rating. |
How much is a Plymouth Duster worth?
There is no single useful price for every Duster. Compare cars by exact year and package, engine authenticity, condition, rust and restoration quality, originality, documentation, transmission and options, and credible comparable sales. Hagerty notes that condition, options, and history affect value, and that documentation matters because lower-powered cars have been converted.
For a dated example, Hagerty’s July 2026 guide listed a 1974 Duster 360 in #3 Good condition at $17,633–$25,833. On the same page, Hagerty reported 19 vehicles sold and $742,700 in total sales volume over the preceding 12 months, with a $39,100 average sale price for 1970–1976 Plymouth Dusters. These are a condition-specific guide range and a stated-period sales aggregate, not a universal asking price or guarantee for an individual car. Recheck current values and compare cars in similar condition before buying or selling.
What to check before buying
- Confirm the year and package. Compare the VIN and available factory documentation with the claimed model and equipment. A VIN alone does not establish that the current engine or other components are original.
- Verify performance-model authenticity. For a claimed Duster 340, check the documentation and physical details against the correct year’s factory literature. Lower-powered Dusters have been converted, so appearance alone is not proof.
- Inspect condition and restoration quality. Look closely for rust, repair quality, and signs of incomplete or poorly documented work. Condition can matter as much as the package name.
- Compare like with like. Use recent, relevant sales or dated valuation data for the same year, configuration, and condition. Do not treat a broad average as the value of a particular car.
- Match manuals and parts to the car. A Plymouth Duster service manual should match the model year and engine. Year-specific sales brochures can also help check period equipment, trims, engines, and colors; confirm edition and availability before purchasing.
FAQ
How many generations of Plymouth Duster are there?
The original Valiant-related Plymouth Duster is best treated as one model generation spanning 1970–1976. Later Plymouth vehicles reused the Duster name but are not part of this guide.
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What engines were available in the 1970 Plymouth Duster?
The 1970 lineup offered 198- and 225-cubic-inch Slant Sixes and 318- and 340-cubic-inch V-8s. Hagerty’s historical overview gives the initial range as 125 hp for the small Slant Six through 275 hp for the high-performance 340.
When did Plymouth replace the Duster 340 with a 360?
The 360 V-8 replaced the 340 for 1974. Hagerty gives the 1976 Duster 360 a 220-hp rating.
What is the difference between Twister, Gold Duster, Space Duster, and Feather Duster?
Twister and Gold Duster were appearance-oriented packages. Space Duster, added for 1973, increased cargo utility with a folding rear seat and carpeted trunk. Feather Duster, added for 1975, used a 225 Slant Six and lightweight aluminum components.
How much is a Plymouth Duster worth?
Value depends on the specific year and configuration, condition, originality, documentation, and comparable sales. As one dated reference, Hagerty’s July 2026 guide listed a 1974 Duster 360 in #3 Good condition at $17,633–$25,833; that range is not a universal value for all Dusters.
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