Surprise - Mono valve - It?s not one?it?s two
 

After getting very uneven heat in my 1987/ 300SE Euro and going through VIN#'s with Phil (and reading my share of threads about the Monovalve), I ordered the repair kit from fast lane.
As always Phil was very attentive and it arrived promptly.
However,since it is my first Mono Valve experience, imagine my surprise when I went in there to "just pop the four screws " and realised once I looked at the replacement part in my hand, that my Mono valve is not a Mono Valve at all. It's a " Dual valve ".
There are two solenoids (or pistons,or cylinders) there to be replaced, not one..
The way to tell - now I know - is look at the cover and count the number of silvery cylinders protruding from the top.
So you may actually need more than one repair kit for your car....