Genem,
There is also an engine casting date code, just above the casting number. Mine is E-13-6, indicating my block was cast on May 13, 1936. This date will be several weeks ahead of the build date of the truck in most cases. My engine serial number is K6489143, so I suspect your truck was built earlier in the year.
Unfortunately, an earlier owner removed the data plate on the firewall of my FB when a heater was installed, so I have no truck serial number or factory code, although I suspect mine was built in Oakland in April or May of 1936.