Earliest 340 production date/number

Typically the model year launch is somewhere in the end of June and early July. They stagger the launches so the engineers can support more than one launch if necessary.

Now to meet the launch at the assembly plant, they would have to build the engines a little bit earlier. Your block may have been in the first month of production. they would need time to cast the block, then send it to the engine plant, machine the blocks, assemble the engines, put a few of the first ones on dynos to test them,. and then send some to the assembly plant for launch.

Keep in mind, that the engine block machine line has to be "certified" before being able to send any parts through. Each station has to run parts, and measure them, and then calculate if the process is "capable". This means that it can stay within it's tolerance. They would have to send at least 30 parts through and measure them to establish capability.

The bores have to be measured for surface finish to make sure that it is within spec. This takes alot of time. I was involved in launching a new hone on a block and it took tons of measuring. The bores have to be measured for size every 45° at 10 levels throughout the bore. Then you have to do "traces" on the bores for surface finish to make sure that they are not too smooth or too rough, and can maintain those dimensions.

After the line gets certified, then they run a batch of blocks, and then assemble them into engines. They will test a few engines for a "quick" test on the dynos at the engine plant, and then send some to Highand Park for design engineering to put on "long term" dynos to verify that they are good.

This line certification is usually run before launch. They call it a "pilot build" and they do one 6 weeks before launch, called PVP (pre-volume production) pilot build in May. This is where they would certify the machine lines and get parts testing. Then they launch during the end of June/early July.

Then the engines are sent to the assembly plants to be built into cars. The design engineers are usually present for the first few cars to be "walked" down the line station by station, and helping the assembly operators get familiar with the new designs. Once they get the hang of it, then they start speeding up the line until they reach production volumes.

Your engine may have been run in the early stages of launch.