If you want to know when your engine was built, there is a date of manufacture cast into the side of the block, below the distributor. Some will know this fact, so am posting for any that may not have discovered it. [**correction.....as
was said in comments below......the date is when the block was cast and could be a different year than the car was
made. However, it gets you in the neighborhood for age of the engine.]
I don't know if that number was removed when an engine was re-manufactured by some company.
The top number (on this 1950 Dodge motor) is the year, the two below
the month and day. I would presume this information is on engines in
all the Chrysler brands with flathead sixes. (Anyone with different information feel free to comment.)
And, of course, the I D (or v i n type number) is on the flat boss just
below the head on the driver's side. Here's the one on that same 50
Dodge motor.