Some things are very obvious such as non-original or reconed speakers, non-original transformers, replaced pots, re-tweed, re-tolex, re-grill, etc.
I promise the tables will still be there after you finish reading.
They are not of a concern with dating as only the 2 letter date codes on whichever chart or sticker and the transformer number comes into play for that....
There are other ways but the above is a more accurate method.
The final line contains a date code of two printed or handwritten letters denoting the amplifier’s production date by year (the first letter) and month (the second letter).
There were periods of time when this was not consistently done, (between 19), and there are certainly other examples of short periods of time, and individual pieces, where the dating was simply omitted.