Old OP Cal and SN id help.

[MorningTundra]

Does this look like a redial (or just plain old)? I'm suspicious of the "Swiss" only marking at 6 o'clock.

The case is pretty battered and pitted and I'm having trouble making out the Cal and SN. If you zoom in, you can see they're there, just not legible.

I think the cal says 65(?)18. Does that seem right? Google image search gives similar but not the same (different 6 and 9 o'clock markers).

As for the SN, it's a mystery. I can make out two rows if markings. The top row seems to be a 5 digit number. The bottom row seems to be 12 alphanumeric characters. Which one would be the serial?

Unfortunately, I don't have the tools to get the case back off (sorry).

I don't think the bracelet is original (78350-19 and 557 end links) as the clasp is marked 78350 H. I think an H is circa 1970?

Any advice, comments or pointers from the seasoned pros here would be much appreciated.

Thanks