Your post is what inspired my question, as well as a further question. Here's a pic that shows the "finger" in question (I lifted it from the Wool Jersey site so credit and thanks to Morgan Fletcher, it's from his 1963 PX-10):

Now, I have added a yellow block that indicates the area where the word "SIMPLEX" is often cast into the dropout, unlike this where it's engraved in the flat face of the clamp area. Anybody know more about the dates when these 2 different treatments were used, or whether it's actually 2 different styles of forged DO? (Morgan's is stamped LJ Simplex)