I imagine that these are only available on the SnapOn truck, so you might have to flag down a truck, or find a buddy who works in a shop who can order it. (Or, I could get you one...)

There is only one version (I think), which comes with all cables for most European cars (including Mercedes). Note that for w140 cars, you can only get AC and airbag DTCs (which I think are the only codes available on this car...)

www.snapon.com/eurocheck

-David