Do you mean replicating the ink stamp when a fan is being restored? If so there are ink stamps made for that now (as well as the "Engine Side" stamps) I've also got my own in the works because I'm not happy with the accuracy of the current versions.

The part#'s being stamped into each of the blades vs the ink stamped versions (and a 3rd version with just a small pentastar and number without the full part#) was a variable depending on when your car was built. I think more info. is needed on this topic concerning which is right for which application, year, etc.