These are GM's own documents: factory brochures, dealer ordering guides, specification sheets, VIN and model coding, and engineering data. They are linked directly so you can read the original rather than a paraphrase.
A kit preserves material as of its revision date, so a brochure in an early kit can be superseded by a later dealer order guide. Treat a kit as authoritative for what it shows, not as the last word on the whole model year.