Marlin dates of manufacture are determined by the serial number. Earlier Marlins have letter prefix, the later ones do not. Your 1894C
is post letter code so take the first two numbers of your serial number and subtract from 2000 for your date of manufacture. For example my 1894C serial number starts with 21, so subtracting 21 from 2000 = 1979, the exact year I bought that one. Give it whirl and see what you get.
336SC