Technical FAQ: Vintage Campy derailleur mounting bolts

Do vintage Campy rear derailleurs have non-standard mounting bolt threads?

Dear Lennard,
Is the threading on the Campy Nuovo Record rear derailleur mounting bolt a different size than the Campy Victory?

I’m rebuilding a mid-80s Trek 760 with some Super Record & Nuovo Record components and the rear derailleur appears to not want to thread onto the dropout (the Victory derailleur that came with the bike threads in just fine). I don’t want to see metal shavings coming out of the dropout after applying pressure to the bolt, so I thought you’d be the person to consult.

Dear Bill,
Geez, I sure don’t think so. I think I’ve maybe put on one Victory rear derailleur in my life, if that, but I certainly don’t recall that they could not be mounted on a standard derailleur hanger.

I’ve put on oodles of Super Record and Nuovo Record derailleurs in my day, and they always fit a normal rear derailleur hanger. And I can’t imagine any mid-1980s Trek not fitting a Nuovo Record rear derailleur. So I think the bolt on your Nuovo Record rear derailleur must be damaged.