Old Schwinn Traveler: I don't know how to attach the derailleur hanger
So I'm very new to bike mechanics (and cycling in general). I wanted to clean this old Schwinn Traveler (~25 years old?) up to use it for commuting. I used a great book and some help from my LBS and it looks pretty good. However, I have one problem. I have no idea how to get the rear derailleur hanger back on. Every picture or diagram I've seen looks nothing like this and I have no recollection of how it was attached in the first place. Pictures are here.
- There is a hole in the hanger where there was a small bolt and a D-shaped nut. I can't seem to find them. Even when I did have them I couldn't determine how the nut would hold this thing on. And there is no corresponding hole in the dropout
- There is a bump on the inside of the hanger that prevents it from lying flush against the dropout. So if I tighten the nut the bump causes the axle to be pushed out, misaligning the wheel.
Has anyone worked with this design before? I'm sure it's really obvious and I'm just missing it but I have no idea. Thanks for helping out.