New to me 1675 circa 1968

[Watchtopian]

Hello one and all,

I recently acquired a 1968 (2.4m serial) GMT 1675 from a dealer that I have dealt with in the past and he’s always been reliable but had a question about the watch.
So from reading the various posts and other site it would seem the 1560 Cal was replaced with a 1570 cal around 1965 but the movement in mine has 1560 engraved on the bridge. Is it normal to see this? My movement isn’t a hacking one either which is inline with that they say online.
Any insight would be appreciated.

Thanks


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