502. The required number of production models that must be made available to consumers in order to compete in NASCAR. However, the car was 3 and 1/2 inches too long to be an advantage that year 84-85. Engine available dealt with this issue to 305 cubic inches, up to 350 cubes (police interceptor). Hence Chevrolet, went with the Monte Carlo and Pontiac went with the Grand Prix 2+2, (even rarer, not many left). Your "bubble back" rear window was the aero advantage they were looking for. In 1988, they switched to Luminas. Hope it helps.