As I mentioned in my previous posting, the suffix "CMJ" gives it away. It was only used in two years, 1974 and 1980. In 1980 it was used for a 305 for a full sized car or a Camaro. Because in your Vin code the second number is a "5", that means it was built for a 1975 car. I hope this clears it up for you! It should be a real sweet engine, it being a police engine!