Plymouth Sold a Duster That Looked Exactly Like the 340 — Most of Them Had a Slant Six Under the Hood

Plymouth’s A51 Twister package put the Duster 340’s grille, stripes and even its hood scoops on cars powered by a 145-horsepower slant six, and Dodge did the same thing with the Demon Sizzler. Half a century later, buyers are still confusing them with the genuine article. Here is exactly what separated the look from the muscle.

Somewhere out there is a Plymouth Duster wearing twin hood scoops, a flat-black hood, Rallye wheels and a set of bold side stripes — and underneath all of that sits a 225-cubic-inch slant six. That car is not a fake, not a clone, and not somebody’s garage project gone sideways. Plymouth built it that way on purpose, sold it through franchised dealers, and put it in the sales literature. It was called the Duster Twister, and its Dodge cousin was the Demon Sizzler. More than fifty years later, these are still the most misunderstood cars of the muscle car era — mistaken for real 340s by hopeful buyers, waved off as posers by purists, and quietly respected by the people who actually know what they are looking at.

The Six-Cylinder Duster With 340 Hood Scoops Was Never a Mistake

Uncle Tony’s Garage spent a little over seventeen minutes untangling this exact confusion, and the video has drawn more than 218,000 views because so many enthusiasts have run into one of these cars and walked away scratching their heads. The premise is simple: at the start of the 1970s, American performance was at its absolute peak, but the cost of owning it — insurance surcharges, fuel, maintenance, tires — was climbing faster than the horsepower ratings. Detroit’s answer was a whole category of cars that delivered every visual cue of a muscle car and almost none of the running costs.

The viewer response tells the story better than any spec sheet. One commenter described working as an apprentice mechanic at a JC Penney auto center in 1977, changing the battery in a Duster with hood scoops, and realizing partway through the job that the engine bay held a slant six. He asked the owner whether the hood had been swapped after an accident. She told him no — that is how it came off the dealer lot, and she liked it exactly that way. He said the question bothered him for decades afterward. Another viewer made the point that plenty of buyers deliberately saved money on the sticker with a look-alike, planning to add the performance parts later once they could afford them.

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Ford Fired First With the Maverick Grabber

Credit where it is due: Ford got to this idea first. The Maverick Grabber arrived as a mid-year 1970 package and gave buyers loud exterior colors, body-color racing mirrors, a blacked-out grille and rear valance, flat-black striping, a spoiler and larger tires — the entire visual vocabulary of a performance car, with the ordinary Maverick drivetrain underneath. It worked well enough that Ford kept the Grabber on the books through 1975.

Chrysler was watching, and Chrysler had a very practical reason to respond. The company had spent most of its 1971 tooling budget developing parts for the Duster 340 — a genuinely limited-volume car. Plymouth’s marketing people wanted more mileage out of those new tools, and the answer was to sell the 340’s appearance to buyers who were never going to order the 340’s engine. The Twister package, order code A51, was announced in February 1971 and could be had on six-cylinder and V8 Valiant-based cars alike.

What You Actually Got — and What You Definitely Did Not

The Twister package was surprisingly complete. It included the Duster 340’s grille, bias-belted tires on 14-inch Rallye wheels without trim rings, dual racing mirrors, a flat-black hood treatment with a strobe stripe, longitudinal body stripes carrying the Twister logo, and lower deck stripes. The detail that has caused the most confusion in the decades since was an optional item: a pair of non-functional hood scoops lifted straight off the 1971 Dodge Demon 340. Order the scoops, and from ten feet away — or from behind a for-sale sign — the car was very hard to tell from the real thing.

Dodge ran the same play on its side of the showroom floor. The Demon Sizzler became available March 1, 1971, as a dress-up option on the base Demon. Chrysler documented thirteen possible features for the package, five of them included at no charge, among them a color-keyed grille collar, Rallye wheels, bodyside tape stripes and the black hood treatment. Dual color-keyed racing mirrors were among the extras. One line in the order guide matters more than all the rest: the Sizzler could not be ordered with the 340. Base engines only, which meant slant six or 318. Production estimates for Sizzler-equipped Demons vary widely, with figures commonly cited anywhere from roughly 1,200 to 3,400 cars, so exact numbers deserve caution.

The Real 340 Cars Are the Reason Any of This Happened

None of these appearance packages would exist if the Duster 340 had not been so good. Plymouth’s 340-cubic-inch LA small block carried an official rating of 275 horsepower gross and 340 lb-ft of torque through a Carter four-barrel, and by 1971 Chrysler was publishing both gross and net figures — the same engine showed 235 horsepower net. Period road tests generally put the car in the 14-second quarter-mile bracket, which was serious company for something that undercut most big-block intermediates on price. Compare that to the 225 slant six, rated at 145 horsepower gross in 1970, and the gap between a Twister and a real 340 becomes very easy to understand.

The market noticed, and then it moved on. Roughly 24,800 Duster 340s found buyers in the 1970 debut year; by 1971 that number had fallen to 12,886. Over on the Dodge side, the Demon name itself did not survive the era — complaints from religious groups over the name and the pitchfork-carrying mascot led Chrysler to retire it after 1972, with the car returning for 1973 as the Dart Sport.

How to Tell What You Are Actually Looking At

If you are shopping one of these cars, this history is not trivia — it is money. A Twister or a Sizzler wearing scoops, stripes and Rallye wheels can be listed, honestly or otherwise, in language that sounds a lot like a 340 car. The engine code in the VIN and the information on the fender tag are what settle the question, not the hood. And there is a flip side worth saying out loud: an original, documented Twister or Sizzler is a legitimately interesting car in its own right, a snapshot of the exact moment the industry worked out that the look of performance could be sold separately from the performance itself. Buy one knowing what it is, pay what it is actually worth, and it is a thoroughly enjoyable piece of Mopar history.

Watch the full video above and let us know your thoughts in the comments.