The 43-Unit Super Duty Pontiac That Hid Trans Am Hardware Without The Decal
The Pontiac Firebird Trans Am is one of the most iconic American muscle cars ever produced. Its shaker hood scoop, that unmistakable “screaming chicken” decal, and big-block power in the engine bay — all these things combined made the Trans Am an absolute legend. Not only that, but it also appeared in the 1977 film Smokey and the Bandit, which cemented its image in pop culture and made it famous far beyond enthusiast circles. Pontiac offered an array of exciting V8 engine options throughout the car’s lifespan, such as the 400-cubic-inch Ram Air III and IV. Something even better arrived in 1973, but it only stuck around for two years before kicking the bucket.
The Super Duty 455 Was A True Fire-Breather
As cool as Pontiac’s 400-cube V8s might’ve been, it was the Super Duty 455 that really took things to the next level. Also known as the SD-455, this 7.5-liter goliath made up to 290 horsepower and 395 lb-ft of torque. These numbers may not sound that crazy at first, but they were actually quite respectable given the switch to SAE net ratings which took place in 1972. And with that kind of power at its disposal, the Trans Am SD-455 could finish the quarter-mile run in approximately 13.75 seconds. Additionally, it reached 60 mph from a standing start in under six seconds, even as other muscle cars were quickly losing their edge in light of stricter emissions regulations, lower compression ratios and, of course, the oil crisis. But even though the Trans Am tends to be the center of attention, another Firebird variant with Super Duty power is what we’ll be focusing on today.
Pontiac’s Fabled Muscle Car Had A Lesser-Known (But Equally Awesome) Sibling
The Trans Am SD-455 was only offered for two years and produced in very limited quantities — 252 units for 1973 and 943 the following year. That adds up to a grand total of 1,195 copies, but what if we told you there’s a Super Duty unicorn out there with a mere 101 examples in existence? It is all too often overshadowed by its more popular sibling, and Pontiac made just 43 units in ‘73 compared to 252 Trans Ams. The model was more of a sleeper, too, with that iconic shaker hood scoop being the only real thing that gave away its big-block potential. Here is a closer look at what makes this classic rarity so special.
The Firebird Formula SD-455 Is An Understated Gem From The Good Old Days
Enter the Formula SD-455, a fascinating case of Pontiac taking a good look at where the industry was headed and deciding to make its big-block aspirations go out with a bang. The timing was just as interesting as the hardware itself, because the Formula and its close relative were given the high-performance Super Duty treatment right as the muscle car heyday was coming to an abrupt end. As for the engine itself, it had things like a reinforced block with four-bolt main bearing caps, round-port cylinder heads and forged aluminum flat-top pistons paired with forged steel connecting rods. Air flowed in through an 800-cfm Rochester Quadrajet carburetor and a cast iron intake manifold, but that shaker scoop protruding from the hood was actually more of an ornament than something functional.
Although it served a very real purpose on earlier Trans Ams, Pontiac was forced to have it sealed in order to meet federal noise regulations. This hasn’t stopped the SD-455 from making close to 300 hp and 400 lb-ft of torque, though, and that horsepower figure actually sat at 310 before the engine had to be slightly detuned for compliance purposes. Compression was rated at just 8.4:1 despite the high output, while the transmissions available on the Formula SD-455 were either a three-speed automatic known as Turbo-Hydramatic 400 or a four-speed manual. And of the 43 examples built for the model-year 1973, just 10 were ordered with manual gearboxes and are extremely sought-after by collectors today.
Available upgrades included a Safe-T-Track rear limited-slip differential and Pontiac’s Y99 handling package, which gave the Formula an array of heavy-duty suspension goodies and sway bars among other things. But in stark contrast to the Trans Am’s flashy appearance, the Formula was notably more restrained save for that hood scoop and the SD-455 lettering adorning it left and right. There were no screaming chicken graphics or standard spoilers, though, and the Formula’s interior was also fairly subdued compared to its sibling’s. In terms of real-world performance numbers, the Super Duty-powered Formula could go from zero to 60 mph in just 5.4 seconds.
It was also slightly faster than the Trans Am SD-455 on the quarter-mile, depending on the source, with available data pointing to a recorded time of 13.54 seconds. Then there was the pricing aspect, as the 1973 Firebird Formula had a base MSRP of about $3,276, and the SD-455 engine option commanded an additional $675. By contrast, the standard Trans Am was priced starting at $4,204, with an additional $521 required to add the Super Duty engine option. So, in total, the Formula SD-455 came to $3,951, while its bolder Trans Am relative was considerably pricier at $4,725 before other options. And with the Y99 handling package installed, the Formula’s price rose to a little over four grand.
Where Pontiac’s Rare Super Duty Sleeper Stands Today
Given the model’s rarity and charming character, you might expect it to demand a premium over the more common Trans Am on today’s market, but that’s not necessarily the case. Interestingly enough, prices tend to fall mostly in the same range for both cars, even if one of them is much harder to come by. For instance, a Bring a Trailer listing from January 2026 shows a pristine 1973 Formula Super Duty owned by the same family since it was brand-new. The unicorn was one of 33 automatics produced that year, and it ended up fetching $110,000 once the auction came to a close. Of course, manual examples will rake in a lot more, but we’re entering the realm of speculation here since recorded sales are virtually impossible to come by. And with only 28 manuals produced across both model-years, that doesn’t come as much of a surprise at all.
One can gain some valuable insights from Trans Am sales, though, because the discrepancy between manual and automatic SD-455s is absolutely huge. Classic.com states an average price of about $114,000 for the Trans Am Super Duty, but then you’ve got a well-kept, single-owner manual example on Restore a Muscle Car with an asking price of $249,900. And that is not even the most remarkable one currently available. An immaculate specimen, finished in Buccaneer Red and with just one mile on the odo, is up for grabs on the same website for a cool $350,000. We can thus extrapolate and get at least a vague idea as to how much a manual Formula SD-455 might cost. Needless to say, it wouldn’t be cheap by any stretch of the imagination.
All the mystery surrounding the Trans Am’s more obscure relative is a big part of what makes its story so compelling, and that allure is only compounded further by its scarcity and sleeper identity. The historical context in which it existed adds yet another layer of fascination to the whole affair, because an engine like Pontiac’s Super Duty 455 should’ve had no business being around at a time when the Malaise Era was well underway. It remains to be seen whether a manual Formula SD-455 will eventually surface at auction, as it would certainly cause quite a stir among collectors in the United States and beyond. It remains to be seen whether that will happen in our lifetimes, or perhaps someone will one day stumble upon the most extraordinary barn find imaginable.
Sources: Hemmings, Hagerty, Classic.com, Bring a Trailer, Restore a Muscle Car, Pontiac
Related posts
Latest Post
No Comments