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Are these backplanes? Something else?

I think you could go backplane or goldfinger cards.
In my opinion, both would be correct, so it's kind of up to you.

Do the slots have gold connectors in them? It doesn't look like they do. But. Light refraction can make gold contacts appear silvery. If they are gold contacts. Those boards will be accepted as Clean Gold Finger Card. If not gold contacts. We need more experienced e-scrappers to chime in.
Here to learn like everybody else

Honestly never thought to do this before but this is what I found when I removed some of the black plastic. Hope this helps. Thanks.