You know I never thought to remove them and look. So I went out to the garage and did:
The back of the three tags:
The fender with them removed. Is that circled spot a mounting hole? (Don't blame me I didn't paint the engine bay black):
The tags separated:
"B" tag (what is this anyhow?)
The main tag
The extra tag
Lining up the paint lines and stains, I think this is how they went together:
Time for a test fit (I left the "B" tag off because it's small and I didn't want to drop it)
So it looks like that is a mounting hole. Unfortunately it's filled with who knows what and needs to be cleaned out before I can mount the tags proper.