Brian,
As I suggested, AMK 's book has a whole chapter on SEMS, etc. and what they all mean. Ford MAY have used a particular stamped bolt, in a particular spot, and in a particular plant during a particular time frame, but you will be hard pressed to find out which.
If you order AMK's fastener kit for THAT particular location on the car, you will get ONE of the head markings that is correct but it may not be exactly the same heads that YOUR car had.