Just open the hood and look on top of the radiator support, there are numbers stamped into a plate that is screwed down to the top of the support, I'm sure you've noticed it. Just look for the set of 6 numbers that start "201.___"

The entire number is the exact model designation. 201 is the chassis number, the other 3 numbers more specifically identify the model. In the US anyways, the earlier 190E 2.3's were 201.024, the later versions were 201.028. I am unsure what occured to make the model designation change, usually it remains the same.

Gilly