I spoke with Bradley Dennis yesterday.
He confirmed that Paul McDuffie and he were both on the SEDCO team, and that is where they met.
They became friends, and when Chevrolet stopped supporting them, the 2 men went into business together in Atlanta Ga, and created the "Atlanta Tune Up Service".

Mr Dennis told me that "Chevrolet sent us the cheapest cars they could, to make race cars out of them, and that was all there was to it."
He later added, "They sent them down by rail from Detroit, because the frames were stronger".
The Atlanta plant had a different frame than the 1 piece frame from Detroit.

He did not remember exactly, but he thinks they put the six lug axles on the cars at SEDCO. He said they had them "lying around".

Bradley Dennis and Paul McDuffie's Atlanta Tune Up Service built cars that were driven by great racers, such as Fireball Roberts, Larry Frank, Speedy Thompson, Bob Welborn, and Joe Lee Johnson.  Submitted by  tommyhawk

The former chief engineer of Hudson's  racing program, Vince Piggins, agreed with GM vice president and general manager of Chevrolet, Edward N. Cole, to move down to  Atlanta and setup the "Southern Engineering and Development Company" known as SEDCO. This company appeared on paper as a division of Nalley Chevrolet Inc. Atlanta, GA. This is where the era of the "Black Widow" began. SEDCO choose the black and white color scheme for their race car.

As to how many of these cars were built? No one seems to know for sure. If there were official records, they didn't survive.

The black and white fuel injected 150 two door sedans appeared at Nascar's National Speed Weeks in Daytona in February 1957.

There are many rumors and myths. As more facts come in, this section will grow.

The reason there are no factory production figures on the “Black Widow”, is because it never rolled off Chevrolets production line.

These competition cars were also made by individuals and groups participating in stock car racing.

April 19, 1957 Chevrolets Central Office sent a letter and booklet to four hundred and eleven dealerships, this was called, 1957 Stock Car Competition Guide.
See Competition Guide Info

Stock car racings national championship was won by Buck Baker in one of these cars, known as “Black Widows”……..

“Black Widows” were all painted black and white.    No kidding……. The other most noticeable item is the six lug wheel set up on all four corners.

The Automobile Manufactures Association prepared a resolution to stop all participation in racing. This was brought on by pressure from congress. GM endorsed this on May 23, 1957.

On June 6th, 1957 Ed Cole instructed Vince Piggins to close down the SEDCO operation, due to the GM endorsement on May 23, 1957.

It's not certain about what happened to the remaining parts and cars left over at the time of this shut down.

We do know the Black Widow went on to win the championship and to this very day, people are still building their tribute to the "Black Widow".

The 1957 stock car racing season, NASCAR limited induction systems for convertible class, short track class, and pacific coast divisions, to the single four barrel carburetor only. Elsewhere the top division could run the hottest stock system available. This was the Chevrolet mechanical "Fuel Injected" 283HP engine.

April 23, 1957 NASCAR rewrote their rules to establish a four barrel carburetor only rule. The "Fuel Injected" Black Widows seemed unaffected by this. Buck Baker went on to win the National Championship using one single 380 CFM four barrel carburetor. These were awesome cars.

In 1957 congressional hearings were conducted about stock car racing. They claimed the automakers racing advertisements were contributing to racing and reckless driving on the road. During February 1957, the Automobile Manufactures Association prepared a resolution suggesting all manufactures stop auto racing activities, and that type of advertising, including the support of private racers.

 Other known facts welcome!