They made up new stamps for each engine suffix code everyday at the engine plant, they just reached into the box of indiviual characters and pulled one out and placed it into the stamp handle. The 1's and I's were mixed together, as was the 0 and O's. You can't really tell a restamp from an original unless you have a known example from the same day, unless the restamp is really horrible, or not gang stamped, of course.