67 Dart GT Rocker Molding Trim Clip???

0.285" = 9.14/32" ~= 9/32"

What an odd size!
Factory punched hole?

Any chance there is 0.030" of paint / rust on the ID of the hole making it a 5/16" (0.3125)

Well either way I have a better starting point than I had before.

Thanks.