No worries Adriano
From a certain angle, I guess also depending how the rudder is pointing, the digit 8 can be seen as a digit 3,
since the far end of the digit gets slightly hidden.
I have only one photo of 45-8663 myself and the 8 can indeed be taken as a 3 if one is not careful and check
the known s/n ranges.
If you also read through what you say with regard to "53-663" and the fact the photo was taken in Aug 1950,
there is no way a Fiscal Year 19
53 aircraft can photographed in 19
50.
Cheers
Stig