Import / sales records for M Series cars in the US?

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Does anyone know if any records have survived (from Gerry Sagerman or otherwise) with details about M Series cars being imported and sold in the US?

I'd really like to know the full history of my car (1979 3000S), which I believe has had two previous owners. I've spoken to the second owner on the phone but he didn't recall any earlier history about it.

--Colin