You have stumbled upon the odd item that is cheaper from the dealer. This rarely happens.

ZF Friedrichshafen AG (parent company)/Lemforder is an OE supplier for MB. They make good stuff, but I would not expect any sort of performance upgrade.
Odds are good that the parts are identical. This 'loose' OE supply line is why German car parts are usually much cheaper outside of the dealership.

A lot of Lemforder parts are manufactured here in the USA. They have a suspension plant in Maine, among others. Drivetrain plant in Greenville SC, near BMW, and many more.
The whole thing is like a 10 billion dollar conglomerate.

Trivia tidbit:
ZF Friedrichshafen AG was started in 1915 by German Count Ferdinand von Zeppelin to make the transmissions for the airships that bear his name.

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1986 300E 5-Speed 240k mi.