I looked at my car to refresh my memory.
There is one rivet in the top of the inside of the radiator opening. But, I think it was a body assembly rivet by ERA. There isn't any frame member there. It might have had a screw in it originally and I removed it and installed a rivet. It probably could have just been filled and painted over.
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In front of the hood opening, I just reinstalled the screw that ERA had installed to make sure that I retained the alignment with the frame. Because that was a square tube frame member, I believed I would be able to get a really strong epoxy bond to the body and I didn't think a couple more screws or rivets was going to do anything further for it. You can just see it in on the underside of the tube member.
At the
oil cooler opening, because that was a round tube frame piece I wasn't sure how much good of a contact area I was going to get with the body to epoxy. So I installed three rivets just to be a little safer.
I guess I need to get a tooth brush and clean the polish off of the rivet heads. Of course the best answer would probably be to talk with ERA and see how they have been doing it.