I don't know the answer either, but I do know that such a distinction goes back to the very first bombs. Only "Silverplate" B-29s were certified to carry atomic

I don't know the answer either, but I do know that such a distinction goes back to the very first bombs. Only "Silverplate" B-29s were certified to carry atomic weapons. <https://en.wikipedia.org/wiki/Silverplate https://en.wikipedia.org/wiki/Silverplate>