The shortest ratio I recall from the era on USA cars was a 3.46 used on the 300SE. I believe it used the same axle housing at the six-cylinder 124s. You refer to a 185 mm axle, which is probably the ring gear diameter, but I haven't heard the axle described that way before.

The early four-cylinder 201s used a smaller axle housing, but I think all later 201s both four and six used the same basic axle (and transmission) as the six cylinder 124s.

The above refers to USA vehicles. Other markets may be different.

Duke