[JoeC]

The ZL1 Covette was RPO. Although it was not advertised, the sales were limited mostly by price. Chevy was officially not into racing but they produced the raw material to qualify for racing. They made the cars to meet the rules of the racing organization. There was no minimum production number required for the complete ZL1 Corvette to compete in road racing but the engine had to be an option that was available. Many racers just bought the engine and upgraded their 68 or built a 69 Corvette race car and ran L88s and ZL1s at Daytona, Sebring, LeMans. etc. In 1970 Chevy built 25 ZR1 Corvettes LT1 M22 with other upgrades for racing. In 1971 there were 8 ZL1 and 8 ZL2 Corvettes built. (I think these numbers are right by memory)
For TransAm racing, there was a 1000 car minimum (Chevy got an exemption in 67) but then special parts were allowed if they had GM part numbers and were available over the counter. This is why Camaro had cross ram, JL8, cowl hood, spoilers, etc. available some as service items some RPO.
Drag racing had different set of rules to meet. In 1963 the Z-11 drag car was RPO and met NHRA 50 car minimum. In 68 the L78 TH400 Nova used COPO process to make 50 car NHRA min. In 69 COPO process was used again for drag cars to meet a 50 car minimum. In 1970 Chevy did last ditch effort to make a mass produced hi hp big block and went back to RPO to produce a 450hp Chevelle not available in Camaro Corvette or Nova.
NASCAR had their own set of crazy rules that they changed often. Some rules required 500 engines had to be built but could be used in other models then they were sold with. NASCAR rules created the wild aero cars. Even in 1986 and 87 Chevy had the SS Monte Aero Coupes special built at great cost in order to get a 5 mph top speed increase at Daytona and Talladaga.
Ok I'm rambling but point is, Chevy did whatever was required to get cars on the race track and into winners circle. [img]/ubbthreads/images/graemlins/biggthumpup.gif[/img]