[Kurt S]

Marlin,
The usage of the LT1 may not have been documented completely (no real surprise since no changes to the engine assembly were required and it was low volume). GM would never issue a new engine code if the engine assembly was exactly the same. Notice how GM commonized their engines in the 70's so they could use the same engine is several car lines.
But this is the build list for the plant to make the engine. It had to be correct or they couldn't build it. Very different item.
Usage tables are notoriously inaccurate and hard to keep updated. Bill of materials have to be accurate because they are used by the engine plant.