looks like a 63 side molding clip. I think they only go in one or two spots. I don't remember exactly but I think rear on the doors or rear on the quarter.
my confidence on this is about 30%, But I know I have seen them and I usually only deal in first gen stuff
I don't know what you have there. Here's a pic of the 63 side molding clip that is used in the rear 3 holes only on the quarter. It's similar but 1 1/2" long and a little less stud offset than what you have.
Thanks so I have 5 clips with the less stud offset like [B]JIMS63s[/B] shows in his picture and 12 of the clips I first posted a picture. They are the same wide and length, so perhaps these culd also be used as replacement as a 63 side molding clip.