fkrel,
Weldome to H-M and the Atlas/Craftsman forum. "942" is the Atlas part number for a 42" bed. Some beds do have a casting date cast in but (a) the date is often either missing or illegible, (b) it is typically in the format mm/dd/yy, and (c) the date will typically be about two years older than the lathe. The raw castings are allowed to "season" for a year or two before being machined.
From your serial number, your machine was made late 1950 or 1951. However, it is a 10F.
Also, the 10F and QC 42 is an Atlas, not a Craftsman. Up until 1957, Atlas made and sold 9". 10" and 6". And Atlas made and Sears sold, under the Craftsman badge, 9". 12" and 6". After 1957, Atlas made and both Atlas and Sears sold 6" and 12", up until early 1981.