When Chevrolet introduced the 1967 Camaro, General Motors had a corporate edict preventing their new car from carrying an engine larger than 400 cubic inches. They wanted to keep the performance hierarchy intact, so they couldn't have the Camaro threaten the Corvette's performance crown. The problem was that cars like the Mustang and Barracuda could be had with much larger engines.
Don Yenko, owner of Yenko Chevrolet in Canonsburg, PA, knew he needed a more powerful Camaro.So he devised a plan to get around GM's limitation. Yenko ordered L-78 (375 hp / 396 ci) equipped SS Camaros and swapped in the Chevrolet Corvette's L-72 427 ci (7.0 liter) V8 rated at 450 hp. The cars came with a 4.10 rear end, heavy-duty suspension, and your chocie of an M21 or M22 transmission. The exact number of cars produced is 104. Yenko also installed a fiberglass replacement hood similar to the "Stinger" hood featured on 1967 big-block Corvettes and Yenko graphics. There were 54 Camaros built in 1967, making this one of the rarest of Camaros. There are only 12 known surviving first year cars.
Encouraged by the success of the 1967 model, Yenko wanted to continue to produce Camaros in 1968. But Yenko couldn't keep up with the demand for 427 Camaros, so he approached Chevrolet about the possibility of getting factory equipped 427 Camaros. Chevy was reluctant, but the people in the Special Projects Division were eager to give it a shot. According to Jim Mattison, who worked in the division at the time, the result was that Chevy agreed to supply factory equipped 427 Camaros to Yenko in 1968 on the condition that he keep it a secret. Don Yenko agreed. The Central Office Production Order (COPO) was developed as a back door around Chevrolet's performance limits.
Until recently it was thought that all 68 of the 1968 Yenko Camaros had dealer installed engines, like the 67s, but they were actually factory installed. All 1968 cars came equipped with the M-21 close-ratio four speed manual transmission. A large, twin-scooped hood replaced the "Stinger" version, and Yenko badges covered the sides and tail light plate. The COPO model came with upgraded suspension, 140 mph speedometer.At the end of the 68 model year the cars had proven it' was still desirable, and reliable enough to appease the Powers that Be at GM. This led to the birth of two special options for 1969: COPO 9561 and COPO 9737. COPO 9561 was the factory 427 cid Camaro, with either a solid lifter 435 hp and 4-speed manual or a hydraulic lifter 425 hp and an automatic. COPO 9737 was the Sport Car Conversion Kit, consisting of 15" 70-series tires on Rally Wheels, a 140 mph speedometer, and a 1 inch front stabilizer bar. The first COPO 9561 cars were delivered to Yenko Chevrolet in January, 1969.
Since these cars could be ordered by any dealer by 1969, there were many more COPOs built. The best figures are 193 automatics and 822 4-speeds were built, for a total of 1015 COPO 9561 cars. Just as Don Yenko was largely responsible for the COPO 9561 427 Camaros, Fred Gibb was the man behind COPO 9560 - the aluminum block ZL1 427 Camaro. There were only 69 ZL1's built, and most went to racers. The cars carried a base price of over $7,200, of which $4160.15 was for the engine - a huge amount of money in 1969.
Originally there were going to be 50 cars built for Fred Gibb, but desire for the car from other dealers ran the total up to 69. These cars were the ultimate factory Camaros, and are very much sought after today. Ironically, Fred Gibb ended up shipping most of his 50 cars back to the factory to be redistributed to other dealers because he couldn't sell them at the asking price. Some of the cars sat on the lot for 2 years or more before they were finally sold.