Glenn,
The first thing you look at is the engine number pad on the block. If it is the same texture as the rest of the engine, then more than likely it has never been "restamped' thus exhibiting its "original" stamped number that was placed on it when it came off the engine run-in line at Dearborn.
If the engine number pad has been ground down to a smooth surface with a number, more than likely that engine LOST its original number and was restamped with the same number or another due to the original engine and its number were shot for some reason.
That being said, the restamps would not be the original stamp on the engine.
So now you are looking at an engine that has the rough engine number pad surface with a stamped number, let's say *A221545*
Ford had a daily engine log that was kept thus recording the stampings of each day.
So by looking up the number "*A221545* say on Bob Johnson's site or my site, you will see that it was stamped on June 29, 1928 and there were a total of 3118 engines stamped for that day (221159-224276).
Then this mixture of engines were shipped to the many different assembly plants, in not any order, for assembly into a chassis and eventually a car or truck.
So many times, more than less, the engine date is not the date the vehicle was assembled unless it was at Dearborn where it is a known fact that this occurance did occur because of the proxcimity of the engines to the assembly line. The further away from Dearborn, the longer the assembly time period. For instance San Francisco was about 2 weeks!
Pluck