Sourcing powertrain parts from other companies or joint ventures with competing makes is common but some makes have their own designs / assembly factories. Automakers make very little of a car, most parts are outsourced. Even if a automaker assembles the transmission, other companies make the parts.

I suspect MB had assistance in designing power train components but they are unlikely to be used in other makes.

New process ( later called New Venture ) makes 4 wd transfer cases, standard transmissions for GM / Chrysler.

There is a recent front drive automatic transmission shared by Volvo / VW / Audi / Ford

GM / Saganaw power steering pumps on plies of 80 and up imports.