[Flojo]

Porsche itself does and did not make these parts themselves, nor were these stamped "Porsche". They were ordered by Porsche to be made for them.
the general manufacturers for such orders were (and still are): Bosch, Magnetti marelli, BERU, Pierburg, NGK and so on.

Same for Sparkplugs, Headlights… quite common in the automotive industry, back then and today.