Canon F-1N odd date code

[muf]

Various searches suggest a letter code for the date, a letter code for the factory and then 2 numbers for the month.
So one of my two F-1N is FB0843 which is F = Fukushima Factory, B = 1987, then 08 for August. The last two digits are an internal code that nobody knows what they mean.

So my other F-1N is what is throwing me. Serial number is an inverted triangle followed by 600. See photo. Does anyone have any idea what this serial number is as it doesn't follow the known serial numbering.

Thanks.

 

[Mackinaw]

That's the letter "V." The ink smeared a bit when it was stamped. The camera was made in June, 1981.

Jim B.

 

[muf]

It doesn't look like a smear, but it's possible. So June 1981 it is!

Thanks.