'CE' Block

[Mr70]

To me this topic is actually asking two seperate questions.
When did service blocks become effective,and when did Chevrolet start coding them "CE"?
I think they've both been answered already.GM was issuing service blocks many years prior to 1968,and I believe 1968 was the first year they started coding service replacement components with a letter prefix to identify their designation with the release of the 5/50 warranty.
C stood for Chevrolet
L stood for Oldsmobile
K stood for Cadillac
B stood for Buick
P stood for Pontiac
Following that,the E stood for Engine and T for a Manual Transmission,H for Hydramatic Trans.,for all cars & trucks.
This also applied to other drivetrain components as well like partial engines,individual & fitted cylinder cases,partial transmission cases and fully assembled too.
I agree that just a "CE" coded block was an over the counter Chevrolet engine sold to the public,and CE block coded CE 012345 was a warranty replacement order for an in house waiting vehicle.