70 AC vent production timeline quiz

[YellowThumper]

As I have been researching and reverse engineering the AC vents for their reproduction, I have identified an anomaly.
Specifically the 70 only right side vent.
Starting with my career background, I am a plastic injection moldmaker. So I have a solid understanding on how their molds were produced.
Now... there is a small feature bump on the lower section of the protrusion that guides the metal push rod.
This "feature" serves no purpose.
The bump is actually a broken off coring insert within the mold. Small "finger" of steel that is missing. Back side of molded face you can see the fracture profile in the plastic.
Guarantee that management made a decision not to shut production down because it was not detrimental to the vents function capabilities.

If this post gets around, it would be nice to find an early build date that does not have the failed mold piece.
FYI my 3D printed reproduction pieces have this anomaly included. Along with all the same split line seams the factory injection molded components have.

Additional info from my geeking world of plastic tooling is that the two sample right side vent assemblies I have. The 70 version and the later 71-74 version were produced by the exact same mold tool. The texture is exact between the two of them. Just like finger prints, there are no identical texture applications to mold tooling. It is produced with an acid etching process.

[captcolour]

If it was from a broken core, wouldn't it be on the inside and not the outside?  Could it be some sort of early poka-yoke so the line operator knew which was the right from the left without looking for RH and LH somewhere on it?

[YellowThumper]

Coring out steel for that ear protrudes upward from the back side. Same reason there is a small shoulder on top of ear feature. Reverse draft from opposing faces as they pilot past each other for the shutoff.
Red marked area shows how small the "fingers" of steel would be on both top and bottom of feature.
Fingers on your hand cupping something.
Same features were modeled into my part. Had to take some liberties for printing strength and visual appearances for the "fake" split seams.

[Fire_Billy]

That's one fascinating find, and your background really adds valuable perspective. Makes sense that management wouldn't halt production over a minor, non-functional flaw.