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Dark Blue Metallic 35

How Many Cosworth Vegas Were Built ?

"How many Cosworths were made?", you ask...

Well, that's a topic worth about a 12-pack of time. Michael Rupert raised this issue with this old (edited)Yahoo! post:


I know that there were supposed to be ~3500 Cosworths built. I keep hearing numbers around 3508.

 In a search of some old CVOA magazines I found at a swap meet, I have seen 3525 and 3554 advertised for sale (as well as 3508).

The thing that makes me wonder is that I picked up 2 motors recently that were numbered 3581 and 3750.

I thought at first, 3581 is believable, but 3750 can't be. The weird thing is that both the engines look just like the others that I have: 

The numbers are in the same places, they have the assembly sticker on the cam cover (though the signature is illegible), everything. I haven't been able to scrape the paint that the previous owners put on the block to get to the s/n, but I will soon. Anyone have any ideas about these numbers?

What is commonly known:

Chevrolet, after a three year development program and a one year delay associated with a failure to achieve EPA certification in 1974, began building the first of approximately 2,061 1975 1/2 Cosworth Twin Cam Vegas (RPO Z09) in March, 1975.
In 1976, a five speed transmission with a 4.10 final drive ratio was added to the option list. A mid model year revision (January 1976) added a sunroof, 8 track tape, and eight additional colors to the option list.

Unfortunately, even these changes did not help the sagging sales of the Cosworth Vega and 1976 production ended in July, 1976 with approximately 1446 produced.

The answer, Michael, is that many have ideas, but nobody has the complete answer. The answer is unclear because there are basically four sets of numbers that are more or less relevant, and there are no complete records.

Those numbers, found on every Cosworth built are:


 1.  The Vehicle Identification Number​

Each Cosworth was given a unique Vehicle Identification Number (VIN), so if every car was registered in the United States, there would be a Bureau of Motor Vehicles record in the state of registry. 

The VIN of the original car the engine was put into was stamped on the block. It will either be 15UXXXXXX or 16UXXXXXX for 75 and 76 respectively. It is located on the top edge of the bellhousing flange, just above the starter location.

VIN located on bellhousing flange.


Look under the windshield corner on the driver's side. 

The VIN tag will be on the metal cowl between the dash pad and the windshield.

In the early 80's, it would have cost upwards of $30,000 to have a nationwide search conducted to sort out and retrieve all of the registered Cosworths. Even if that had been done, it would not have caught the cars that were being held by dealers and never titled. Believe it or not, some of those cars still exist!  For example, #1144 was sold in Atlantic City NJ  in February 2001 after being stored by the dealer since 1975.


Also, such a search would not have caught any Cosworths sold in Canada.


2.  The Dash Plaque

Each Cosworth had a dash plaque with a unique number incised on it. Those started at 0001 and increased. However, the evidence suggests that some may have been flawed or lost or perhaps "lifted" and thus "lost" at the factory. Replacements were available over the parts counter, but only for the numbers exceeding the production run, thus adding to the confusion.

Located on the dash under the convenience "pocket" and above the radio location.

3.  The Tonawanda Number

There is a 4-digit number stamped into the block and the head, and sticker on the cam carrier. Some owners refer to this as the Tonawanda number, as that properly refers to the factory where the engines were assembled. This number does not correlate either to the VIN or to the Dash number, or even to the EFI number.

The Head and Block












                             Cam Carrier Sticker









4. EFI Sticker Number

The 4-digit number on the small white sticker pasted to the various EFI components. The EFI components were calibrated to a "matched set" and the stickers were an obvious way to keep the pieces together.

    An EFI number sticker on the intake mainifold                        EFI number sticker on MAP Sensor     











Large EFI number sticker on Fuel Regulator     

                                                                                          Small EFI number sticker on Wiring Harness              

EFI stickers are also found on the fuel regulator and the electronic control unit.

The Best Thinking To Date

With all this as background, here's the best the minds of Club members can do. Thanks especially to Chris Wheaton, Steve Larson, Paul Wicker, Dick Baumhauer and Duke Williams. Remember, when a 4-digit number is used by Cosworth Vega owners, and at this site, unless otherwise indicated, it refers to the dash plaque number.

Chevrolet production figures list 2061 Cosworths in 1975. But they don't say whether this is the number they made or the number they sold! Chris Wheaton owns a 75 Cosworth, dash # 2069, which is believed to be the last Cosworth produced that year. Chevrolet supposedly did not sell #'s 0001-0006. If one assumes that they did not count those cars for production purposes, but did install dash plaques on them, then that would leave only 2 cars unaccounted for. This can be accounted for if one concludes that two dash plaques were damaged or lost or stolen and therefore never installed. This sounds plausible. But it has never been verified. To make this even more confusing, if GM didn't count the first 6 cars, and then they turned around and sold 0005 and 0006, does that mean that there were 2063 cars sold in 75?

The 76's are a little bit harder because it is difficult to see where the end really is. Chevrolet production figures list 1,447 Cosworths in 76. If you add this 1,447 to 2,061, it puts the total production # at 3,508. But, as in 1975, the dash numbers do not coincide with the production numbers, again possibly due to loss, damage or theft. Thus, #3508 was not the last dash number.  Byron Burnham of San Diego, California has #3509. Chris Wheaton's records reflect dash #'s 3510, 3512, 3513, 3514, 3517, 3520, 3522, 3523, and 3525. Further, Chris suspects that Chevrolet did not sell the first 1976 produced. That would have been dash # 2070.  Even if you don't count that one, however, there still appear to be 1,449 dash #'s for 1976, but again, this does not mean that these weren't lost, damaged or stolen.

"History has told us that dash plaque 3524 was found on a new bezel which was bought over the counter.

Possibly 3523 could have been the same, but it was well worn so it had been on a car for a long time. Either on this car or the real 3523.

It is unknown if a factory car ever came with 3523 on it, but I am still searching for information." -Steve Larson 6/27/01

Contradictory Information Is Suspect


Now, when it comes to other info you read in magazines, don't believe everything you read.  For instance, one member wrote to say he read about Cosworth # 3508. If he was referring to the CVOA Magazine article titled "One Man's Idea of the Perfect Cosworth #3508", that was a typo.  The next issue of the Magazine contained a letter to the editor from Dave Pristash stating that his car was actually # 3505, not # 3508. That car did exist, however. 

Chris Wheaton talked to Carl Bell at HME, and Carl says that they parted out # 3508, and that it was a firethorn, firethorn vinyl car. Michael also said he saw an ad for # 3554, but this was a typo as well. It was actually # 3454. Chris has found several typo's in various magazines and newsletters over the years, and is immediately suspect of such numbers.

Correlation to VIN's, EFI Stickers and Tonawanda Numbers


There is no "official" relationship between the VIN and the dash plaque number. Officially, the dash plaque was just a trim item. However, mining the extensive databases compiled and maintained by Chris Wheaton and Steve Larson revealed a significant correlation between the VIN and the dash number. It appears that about every thirtieth car down the Vega production line was built as a Cosworth Vega model. Further the dash plaques were, with two classes of exceptions, installed in numerical sequence. 

The first class of exceptions is the most significant. Dash plaque numbers from 401 to 500 were "skipped" for some reason. They may have been misplaced, they may have had a flaw and needed to be re-made. The best recollection is that they were "lost in shipping." What is known is that these 100 plaques were not used until after dash plaque #1200 was installed; thereafter production resumed with #1201. 

The second class of exceptions relates to approximately 14 individual missing plaques. Apparently due to the loss, damage or theft of individual dash plaques, some numbers were skipped during production. That is why the highest number dash plaque, 3522, is higher than the total production, 3508. 

At one time early in the process of gathering data it appeared that dash plaque numbers lagged the EFI sticker numbers by about 500 units. Once again, database collection and mining dispelled this myth. It appears that the late production cars have sticker numbers close to the dash numbers. Thus #3466 has sticker #3515. However, this may be nothing more than a coincidence, as #3387 wears EFI sticker 2838. Early production cars were all over the lot. Dash #0803 had EFI sticker #0850, while Car #1002 had EFI sticker #0805. #0539 has EFI #0335, while #0677 has #0716, and #1620 has #0376. Car # 3412 is the only one known where the two numbers actually match.  

Not enough data has been collected to ascertain whether there is even a trend regarding the Tonawanda numbers. Smart money is betting that no correlation exists.  

Best Thinking On Engine Production


As far as the engines go, the best information is that Chevrolet built a total of 5000. In the early eighties GM disassembled about 500, and the rest were scrapped for the tax deduction. Original CV engines installed at Lordstown have the abbreviated VIN stamped on the RH side of the bell housing mounting flange.

Also, there is a three or four-digit number stamped on the rear face of the case, head, and cam carrier. This is commonly referred to as the "Tonawanda number". A "e;matching numbers"e; engine will have the same number stamped on each component. It appears the numbers started at 001 and increased, and as noted above, no correlation has been seen to any other number on the car.

Finally, there is a production location/date code stamped on the top center of the bellhousing flange. It is a three letter, four digit number. In 1975 the letters were "ZCA" and in 1976 the letters were "ZCB". The ZC is Chevrolet code for the Tonawanda plant, and the "A" and "B" appear to refer to the year of manufacture. The four digits represent the month and day the engine was built.

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