3764476 was a truck block code from 1956 through at least 1961
F512J
F = Flint, MI assembly plant
5 = May
12 = 12th
J = 3100-3800 regular production truck (3-speed transmission)
That type/style of engine serial number was used from 1957 onwards.
If you want a date for the block/head,
post the head date casting code and the block date casting code.
