Like everything else, can be faked. The solid axle or straight axle cars. Mid-years and Sting Ray years. Includes 1968 Shark, and 1969 - 1976 Stingray years. There were no 1983 production cars due to plant change over from St. Louis to Bowling Green.
Many castings also have a date code cast into the part as well.
Parts such as blocks, manifolds, heads, transmission cases, differential cases and many more have casting numbers that identifiy them as particular to certain applications. On most Chevrolet blocks the casting number is located on the bellhousing flange behind the driver's side head. This can usually be seen even with ignition shielding in place. Convertible Cars with a fold down canvas like top, and roll up windows. The order was generated through the Chevrolet Central Office.