Not a cheap part -

http://catalog.peachparts.com/ShopByVehicle.epc?q=1993-Mercedes--Benz-300sd-Climate--Control&yearid=1993%40%401993&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6211:ED|10000113:MBC|1511%40%40300SD&catid=242213%40%40Climate+Control&subcatid=242297@@Blower+Regulator&mode=PD

Don't forget some heat sink grease for the aluminum base.

Sixto
87 300D