Reading an article about Fender (the guitar company years ago, an employee stated that as parts came in the went into bins. There was no effort to use them in order.

That is why, on a later instrument, you can see an older serial, as the serial is on a separate metal plate.

I think some of the same thing went on at Altec. I do think, as older parts were discovered at later dates, Altec made an effort to use them up primarily in OEM versions. Most of the real oddities I have seen came in cabinets, not retail versions.