Starting in 1973, the year of manufacture may be determined by subtracting the first two digits of the serial number from 2000.
Example: SN 2512345 would have been made in 1975 [2000 - 25 = 1975].
Where the SN begins with 00, 99, 98 or such, subtract from 2100 to get the year.
Example: SN 995460098 would have been made in 2001 [2100-99=2001].
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