Here is a link to an adapter kit for OM617 to 700R4 or any GM auto, he claims that the stock mercedes converter does not multiply the torque and I guess is just a fluid coupler. Is this correct ?

You forgot the link...
http://www.transmissionadapters.com/Merc...diesel.htm

These are the folks that I've been in touch with to adapt a GM V8 pattern to an OM606.

I can't speak to the older Merc torque converters, but I know on my 722.608 the lockup varies between 5 and 95% depending on conditions - so it never fully locks up like most GM, Chrysler and Ford torque converter clutches. Unfortunately, the way the world is going - the domestics are starting to go the variable lockup route, in lieu of a binary locked/unlocked scheme, since it allows for a smooth drive with less NVH...at the sacrifice of some efficiency.

Beers,

Matt