Formula 1 cars in "series" production?

[TimD]

Well, not quite!

But I was reading this morning a piece about the Lotus 16, and how careful study of the appalling Lotus factory records, and magnifying glass examination of contemporary photos, brought some researchers to the conclusion there must have been five chassis that came out of the Lotus works.

Which led me to wonder, what is the Formula 1 car which has had the biggest production run? Presumably it will be one of the cars from the privateer era, as the factories will have been churning out customer cars to sell.

Or was it some design that was entirely run by the works, but was driven exclusively by Andrea de Cesaris....