There about four or five types of wiper connectors used by ALL of the vehicles manufactured in the world. So, most wiper manufacturers, (wanting you to purchase THEIR brand of wiper), sell a generic wiper arm. Included with the arm is a variety of "connectors", each designed to attach to their wiper and at least one of them is compatible to the "hook" style arm.
By the way, the hook style is not unique to the "mono-arm" style. My other MBs (and my Bug) all have the same type.
Domestic cars seem to come with the "locking spade type", as in my Chrysler Conquest, which by the way, also is fitted with the same Bosch wipers.
My 93 300E also has the mono wiper arm, and the fit is perfect.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car