1970 Plymouth Duster

The 1970 Plymouth Duster was a brand-new model for Plymouth, created by taking the practical Valiant compact and reshaping it into a sporty fastback coupe. It was Plymouth’s answer to the growing demand for affordable performance cars during the muscle car era.

1970 was the debut year of the Duster nameplate. Sleek semi-fastback roofline with a shorter deck than the Valiant sedan. It Shared front clip and dashboard with the Valiant, but rear bodywork and profile were unique. The Interior was simple but could be dressed up with trim packages. Interior Options were Bench Seat (standard) or optional bucket seats with console (on Duster 340s). Carpet standard on 340, optional on base cars. Choice of basic gauge cluster or optional Rallye cluster (tachometer, oil pressure, ammeter). Optional AM or AM/FM radio. Heater/defroster standard, air conditioning optional (rare on 340s due to performance focus).

Total Plymouth Duster production was 217,192 units, with the Duster 340 at 24,817 built. This strong launch made the Duster one of Plymouth’s best-selling cars in the early ’70s.

Trims offered:

• Duster (base) – economical, Slant-6 powered
• Duster 340 – performance model, positioned as a budget muscle car
• Duster Twister (introduced later) – appearance package
• Engines & Performance

Base engines:

• 198 cu in Slant-6 (125 hp)
• 225 cu in Slant-6 (145 hp)

Optional V8s:

• • 318 V8 – 230 hp
  • 340 V8 – 275 hp (Duster 340, the hot performance version)
  • 360, 400, and big-blocks came later in the 1970s, but not in 1970.

Transmissions:

• 3-speed manual
• 4-speed manual (with floor shift, available on 340)
• 3-speed TorqueFlite automatic

Duster 340 performance:

• 0–60 mph in ~6.0 seconds
• Quarter mile in ~14.5 seconds (very quick for its price point).

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Appearance Options

• Stripes & Decals:
  • Duster 340s got the bold “hockey stick” side stripe with “340” callout on the quarter panel.
  • Stripe colors varied (black, white, or red depending on body paint).
  • Twister package (introduced later, but hinted in ’70) emphasized graphics-only performance styling.
• Vinyl Roof: Optional on all trims, either full or partial coverage.
• Paint Colors: Wide range of high-impact Mopar colors available (TorRed, Lemon Twist, Lime Light, In-Violet, etc.).
• Wheels & Tires

• Base models: Simple hubcaps or optional full wheel covers.

• Duster 340:
  • Rallye Road Wheels or body-colored steel wheels with “dog dish” hubcaps.
  • F70x14 or G70x14 bias-ply tires (performance rated).
  • Optional white-letter Goodyear Polyglas tires.

Performance & Handling Options

• Sure-Grip Differential (limited-slip): A must-have for traction in high-power models.
• Rallye Suspension Package:
  • Heavy-duty shocks and springs.
  • Front sway bar.
• Manual Steering or Optional Power Steering.
• Manual Drum Brakes standard, with optional power-assisted front discs.

Drivetrain Options

Transmissions:

• 3-speed manual (standard on base models).
• 4-speed manual (with Hurst shifter on 340).
• TorqueFlite 3-speed automatic with console or column shift.

Axle Ratios for 340:

• Standard 3.23:1.
• Optional 3.55:1, 3.91:1, and even 4.10:1 for drag-race setups.

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1970 Plymouth Duster pricing

A 1970 Duster 340, 4-speed, Sure-Grip, Rallye suspension, and stripe package was one of the best bang-for-the-buck muscle cars of the era — light, cheap, and quick enough to worry bigger Mopars and Camaros. Including the base car, the 340 performance package, and key options. Prices are approximate MSRP (Manufacturer’s Suggested Retail Price) in 1970 dollars:

Feature / Package	Base Duster (Slant-6)	Duster 340 (Fully-Optioned)
Base Price	$1,994	$2,400
Engine Upgrade (340 V8)	–	+$358
Transmission (4-speed manual)	–	+$184
Rallye Suspension	–	+$75
Sure-Grip Differential	–	+$45
Axle Ratio (optional)	–	+$25
Side Stripe / Appearance Package	–	+$45
Bucket Seats with Console	–	+$78
Rallye Instrument Cluster	–	+$42
Optional Radio (AM/FM)	+$120	+$120
Air Conditioning (rare)	+$408	+$408
Approximate Total MSRP	~$1,994	~$2,850–$2,900

Base Price

• 1970 Plymouth Duster (Slant-6 base model): ~$1,994–$2,099
• Standard features: Slant-6 engine, 3-speed manual, basic interior, hubcaps, standard trim.

Engine Upgrades

• 225 cu in Slant-6 (upgraded): +$50–$75
• 318 V8 (2-barrel): +$265
• 340 V8 (4-barrel, Duster 340 model): +$358–$400

340 V8 also included upgraded suspension components and tachometer as standard.

Transmission Options

• 3-speed manual (standard): included
• 4-speed manual: +$184
• TorqueFlite 3-speed automatic: +$231

Performance & Handling Options

• Rallye Suspension Package: +$75–$85
• Sure-Grip (limited-slip) differential: +$45
• Performance axle ratios (3.55:1, 3.91:1, 4.10:1): +$22–$34 depending on ratio

Appearance & Interior Options

• Hockey Stick Side Stripe / Duster 340 Stripe Package: +$40–$50
• Vinyl Roof: +$68–$85
• Bucket Seats with Console (Duster 340 optional): +$78
• Rallye Instrument Cluster (tachometer, oil pressure, ammeter): +$42
• AM Radio: +$70
• AM/FM Radio: +$120
• Air Conditioning: +$408 (rare on compact 340s due to performance focus)

Summary of a Fully-Optioned Duster 340 (1970)

• Base Duster 340: ~$2,400
• Add 4-speed manual, Rallye suspension, Sure-Grip, stripes, bucket seats, Rallye instruments: +$450–$500
• Total MSRP: ~$2,850–$2,900

For comparison, a 1970 Dodge Challenger or Plymouth GTX was $3,500–$4,200+, so the Duster 340 was a bargain for a lightweight performance car.

The fully-optioned Duster 340 was still cheaper than most full-size muscle cars of 1970.