I wouldn't eliminate Bosch based on the fit on your Ford. Bosch is a German manufactuer, and might be excused a bit if they didn't get the fit quite right on an American truck. The quality of materials is excellent. They made the originals for you Mercedes and I have installed the kit before and they fit like original.
At this site (Fastlane) they offered SETS by Bosch, Beru, and Bremi:
http://catalog.peachparts.com/ShopByVehicle.epc?q=1990-Mercedes--Benz-300se-Engine--Electrical&yearid=1990%40%401990&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6216%3AED%7C10000012%3AMBC%7C1513%40%40300SE&catid=240798%40%40Engine+Electrical&subcatid=240803@@Ignition+Wire+Set&mode=PD
AND you'd be helping to support this site.
Gilly