I've read about a dozen threads on this site with tips on how to coax stubborn rear drums off a Ford 9 inch, but mine are still on there.

One tip that seemed like a great idea was to take a file to the gap between the hub and the drum face. I did that, but dig as I might, I can't find the gap. It all seems like one piece of metal. Where should the gap be? Does the axle/hub face with the three holes have square shoulders, or are they tapered?

I took a couple of closeups so you can see what I'm dealing with.

As always, thanks for your help. You folks are great.