Is this 5513 a frankenwatch?

[skyfjall]

Hi guys, I am currently looking for a 5513 and came across this post and wanted your guys' opinion since I am rather new to vintage. The dial seems to me to be a non-serif dial (indicated by the '=' being to the right side of 'A' and submariner being below feet/meters)? But the owner states that the serial is 15xxx (and picture #3 would agree with this serial), and that the watch is from 1966, which would mean that it should be gilt dial or meters first 5513 since non-serifs seem to begin at 2xxx (in the year 1969 onwards). Sorry if I missed out on anything as I am new to vintages. Thanks!

s-l1600 (1).jpg
s-l1600.jpg
s-l1600 (2).jpg

[Cheutc]

1966 should be a meters first dial

[Beelzy]

Late 60's watch with a early 70's dial. No Bueno