Date code question

This is the power pack tags that was attached to the block. This should mean that this 273 commando engine was built way before the release of the power pack option for 1965 production. I think they announced it around Sept 20, 1964. Could this be a pre-production engine?

I think most of all the numbers that we are running after is just a date when the product was casted. Not when it was assembled and that is a big difference.

There are some parts that has date codes that make sence, the signal horns, the brake booster, the carburator, the distributor, spark plug wires etc. The date codes were stamped when the part was assembled. The date code on the spark plug wires has the same quarter for three month and then it was changed to next quarter. Simple as that.