Well, I found another one, picked one, and set the other one up on a date with my rotary tool. Here are the results.
From what I can tell, the biggest difference between current American Lock Co. locks (5200's mainly) and this one are the width and depth of the serrations. I believe that's what kept me from picking this one for so long.
The nearly black serrated pin in this picture is from a 5200, so you can see the difference in serrations.
