They are a %$#@!!!!
I just took the passenger side off my 65 Coronet parts car Saturday.
The clip you see is probably 1 1/4" wide. The point were the tabs on the clip lock into the drip rail is about 5/8" left and right of the center of the clip. They are small tabs about 1/4" wide and are fragile. I don't think you want to break these as I have never seen them anywhere. Didn't think about it at the time but I wish I would have taken some pics.