I have been keeping an eye out on German Ebay. There was a few of these months ago. I contacted the sellers, but no luck. But thanks anyway Forced Induction.
As for other engineers out there, I contacted some folks up in WI or MI -- I forget -- and they do a conversion with a common Chevy 5 speed. They actually list their product conversion for the OM617.952 engine on their web page. They only sell the plate and the plate was a bundle. I called them and they indicated that they have nothing to do with anything else in the conversion. By email, they pointed out the obvious, e.g., need linkage, flywheel, driveshaft, et cet. So, assuming that Forced Induction is correct, sticking with MB parts may be cheaper in the long run. Not sure, however, since I cannot locate a Getrag 717.400