Make this note :
"In addition to these service only assemblies, any current production passenger engine assemblies that are ordered by the Parts and Accessories Department for service usage must have a service identification number".
I'm going to jump to a conclusion here. If they ordered an engine for a specific application, say an L-34 350hp/396 engine for a 1968 Camaro it would be stamped "T0309XX" and ALSO a "CEx50001" (with X being the year it was ordered in). That's a lot to stamp on that small pad. But that's what the instructions say they have to do to COMPLETE engine assemblies (as opposed to partial assemblies or universels).
After doing some more research and talking to Al Grenning (Corvette engine guru), I believe that complete engine assemblies that were used for service were only stamped with the CE code. Fran's supposition had a solid premise, but no CE blocks have ever been found that have an engine assembly stamp on them, either in a Camaro, Corvette, or out of a car.
Which means the engine plant would have known that those assemblies were destined for service and did not stamp an assembly code on them.
That also means there's no easy way to distinguish between a CE short block and a CE engine assembly. Heads and other components would be dated for the block, if those components are still on the block.
Are the totals for engine production by engine assembly part # or by application code? Do any of the sheets indicate where the assemblies were destined (i.e. assembly plant or service)?