By the early '70s, the muscle car mania that swept through much of the earlier decade had pretty much run its course. A changed economy characterized by rising insurance rates, effects of the OPEC oil embargo and looming regulations governing emissions signaled the end of the horsepower craze. However, Pontiac was not going to go down quietly and the debut of the Trans Am with its formidable SD-455 engine was proof of that.

Surely, Pontiac must have known the Trans Am SD-455 was never going to last long in the market, but it still did not stop the carmaker from creating what is arguably one of the finest muscle cars at the time.

10 That 'SD' Designation

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via automobilemag

The Trans Am SD-455 was a special breed of muscle car and one of the clearest pointers to this fact had to be the 'SD' designation in its name. It stands for Super Duty and dates back to the early part of the '60s when it was first applied to drag race specialists like the Pontiac Catalina SD.

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via classic

It denoted something really special under the hood; a powerplant capable of truly impressive performances. The fact that Pontiac unleashed the Trans Am SD-455 right at the time when the fuel crisis and emissions regulations were tightening only served to make the car even more unique - a rebel among the flock.

9 Gone With The Wind

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via designcorral

Yes, this is what happened to the Trans AM SD-455, a Pontiac creation with one of the shortest production runs in Pontiac's history. The SD-455 engine was first introduced to the public by Pontiac in 1972.

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via favcars

However, a series of delays which included the need to pass the Environmental Protection Agency's (EPA) emissions tests, meant the first cars with the SD-455 engine did not roll off the assembly line until the later part of 1973. As it happened, the following year would turn out to be the only full model year for the muscle car and they were gone by the start of 1975.

Related: 5 Of The Best Buick Muscle Cars And 5 Pontiacs We'd Rather Drive

8 A Beast Under The Hood

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via pinterest

As stated earlier, the heart of this Firebird Trans Am is the SD-455 powerplant shoehorned under the hood. The engine was a masterpiece; hand-assembled by passionate engineers inspired by lessons learned from the Firebird's participation in the SCCA Trans-Am racing and Pontiac’s 366-ci Ram Air V NASCAR race engine program.

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via davidsclassiccars

Much of the engine's performance advantage lay in elements like its specially designed round-port, open-chamber cylinder heads which were developed together with an aftermarket company.

7 The Trans Am SD-455 Almost Never Happened

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via hagertyinsider

The insane horsepower craze was gone by the early part of the '70s. People were already turning to more fuel-efficient cars to save on rising gas bills. In fact, some brands had seen the sale of their muscle cars plunge by as much as 50% between 1971 and 1972.

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via anjo.spb.ru

Then there was also the tightening of emissions regulations, a result of the Clean Air Act, to contend with. It did not bode well for the Trans Am SD-455 but the engine development was at an advanced stage at the time and there were still a few people within the Pontiac hierarchy passionate enough to push the project through.

6 The Muscle Car Packed Some Serious Punch

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via Mecum

The Trans Am SD-455 was no joke and Pontiac pulled no punches when the car was unleashed. The car was originally rated at 310 hp but certain modifications made to the V8  powerplant brought the power down to 290 hp which was still about 65 hp up on the standard Firebird with a 400 cubic-inch V8.

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via mecum

However, the engine whipped up an impressive 395 lb-ft of torque. It was enough to rocket the car to 60 mph in less than 6 seconds and complete the quarter-mile run in 13.54 seconds at about 104 mph. These performances easily ranked the Trans Am SD-455 among the fastest muscle cars at the time.

Related: 4 Rarest Muscle Cars You Can Buy For Cheap (4 That Cost A Fortune)

5 A Rare Breed

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via rkmotors

There was a lot of anticipation around the impending arrival of the Pontiac Firebird trans AM SD-455. Orders grew at the dealerships but most of the potential customers would be left disappointed.

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via mecum

Pontiac only produced 252 units of the Tran AM SD-455 in 1973, its debut year. The situation improved slightly for 1974 but by the time production wrapped up, there were still less than 1,200 Trans Am SD-455 cars that had been made in total.

4 A Collector's Classic Today

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via mecum

The Firebird Trans Am SD-455 was a bargain when new. It cost about $5,500 back in the day and offered performance that was comparable to rivals like the Jaguar XKE which cost $9,200 or the imperious 454 Corvette that was priced at $6,200.

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via mecum

Today, the Trans Am SD-455 continues to hold up well in the second-hand market. According to Mecum, a pristine Trans Am SD-455 with an automatic option can go for as high as $85,000. The manuals are even more valuable, regularly commanding prices in the 6-figure range.

3 A Pricey Piece Of Equipment

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via mecum

The Trans Am SD-455 was a bargain deal compared to its rivals but that did not mean the car was exactly cheap. It was still pretty much a premium muscle car, costing about $521 over the Trans Am with the 'non-SD' 455 cubic-inch V8 engine.

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via mecum

In all, the Trans Am SD-455 costs about $700 over the base trim Trans Am. That's the equivalent of $3,500 in today's value and thus did not even factor in the dealers who often charged extra for the cars that arrived in their showrooms.

Related: We Can't Stop Staring At These Awesomely Modified '70s Muscle Cars

2 Not The Only One To Wear The SD-455 Badge

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via barrettjackson

Interestingly, the Firebird was not the only sports car from Pontiac to carry the SD-455 badging. When the SD-455 engine program was first conceived, the plan to apply it across an entire range of cars in its lineup. They included models like the Firebird, LeMans, and the Grand-Am.

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via barnfinds

However, according to the regulations, they would have to certify the engine for each model; an action that was bound to eat deep into Pontiac's resources. In the end, Pontiac decided to go with just the premier Firebird Trans Am and Firebird Formula cars. They were the only cars that were fitted with the SD-455 engine for 1973 and 1974.

1 The Iconic Screaming Chicken

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via mecum

It's hard to miss that shaker hood of the Trans Am SD-455. It was a functional air inlet when it was first introduced in 1970. However, Pontiac was forced to close it off for the 1973/74 Trans Am to reduce noise levels.

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via hotrodnetwork

Apart from the shaker hood, the other distinguishing feature of the cars had to be the screaming chicken decal. It was created by Pontiac designer duo Bill Porter and Norm Inouye in 1970 but it was not until 1973 that they became a standard feature on the cars. It was the Trans Am's signature feature through to 1981 before it returned as an option for model years 1985 to 1987.

Next: 10 Muscle Cars from The '70s That Actually Have Power