There's no such thing as a "newer used non-auto system."

Mercedes never made any rear suspension for W124 wagons except for the one you have.

Your so-called mechanic is suggesting cobbling something up.

He's not doing you any favors, and you should seek another mechanic.

__________________
Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles