The OEM engines I'm accustomed to dealing with had a single line of stamped letters and numbers about 1/4" tall on the machined pad ahead of the passenger's side head, and the "Target Master" and other new-manufacture replacement engines had two stamped lines of alpha-numeric code about 1/16" tall with no correlation to the published letter suffix codes.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!