Grumpin, it seems to just be a pad of solder that goes straight onto a copper contact that is part of the window. No hole to help with fastening.
Thanks, gsmblue. I don't think any of my lines are broken, but I will definitely keep this in mind when I do my own tailgate rebuild in the next year or so!
1986 Bronco. 5.0L, Edelbrock Pro-flo 4 EFI, Baumann-controlled 4r70w, 3.55 gears, 31" tires.