The horn is markus klug's wooden 1505.

This will be a long term project. Once the 817 is done I will play with the 288 swapping it out with TAD 2001 or adding a TAD tweeter, to check if it works. I am buying the Altec drivers now because they go up in price. The speaker gets built after I move from my current place to a new one which is a while away.

Ignore the 6, that was a typo. I was about to say the serial numbers are separated by 116 when my mobile when I must have typed in something wrong. Anyway based on what you said the serial number could be done over a period of time. The cones do have 21184-3 however