F523J, Flint plant, built May 23rd, 3100-3800 w/manual transmission '58-'62. If you can find the date behind the starter, you'll get the year, seems the engine build date (stamped number) is usually a few weeks behind the casting date.
No filter is required, as they were optional on that engine. However, if you want to install one, it is very easy to do with some minor plumbing.
On to the serial number. 6FSH2035; 6, Assembly plant; Oakland, CA. F, Year; 1948, F Series; 3800 1 ton, H, Month built; August. Last digits are the basic production sequence number, starting at 1001. The AFCA and AFCM would be them engine codes for the original engine. That number would not be present on the body tag, though it may be on the title, depending on where it was originally titled.
