Dave, the date of your parts book will make a difference as to the wording and applications. A 1970 parts book will list more part numbers than a later one, because as stock of rarer pieces dried up, they would start to substitute parts that would fit those applications.
I knew a woman in North Vancouver who had an original black 1970 W-30 convertible. She decided to restore it, and wanted to replace every part she could, including the engine and drivetrain. She ordered a W-30 short block and heads in about 1978, not understanding that GM just substituted a 455 short block and less desirable heads because the good stuff was long gone. I was in GM parts in the early 70's, and one of my jobs was replacing parts books, or sections of them on a regular basis when GM shipped them to us. Lots of superceded and changed up part numbers.