Amer,

this watch is perfectly legit. These very early 2nd ex Autavia, with serial around 53xxx (like the very last big reg),
had dial with no T, because in 1963 there were not the laws about radioactive emissions.
The late 2nd ex dial, with the T, is most likely seen in the watches with serial 59xxx.

Here is my watch with serial 532xx

Paolo

I found this Beautiful Vintage Heuer Autavia 2nd Execution and
: seems to be all Original but with a very small different details
: as all Autavias modell the swiss script is under the white 12
: register and not inside and also without T........any thought?
: Best
: Amer