Skid Row Joe, thank you. Been looking online for dimensions on the OM606 but so far coming up dry. And if anyone out there has a picture of an ML without an engine in the bay I would really appreciate it.
Once upon a time I put a 6.2L diesel into an El Camino, and it seemed like smooth sailing until the engine was lowered in. Crossmember/oilpan interference, AC box no longer fit in its stock location, the rear firewall had to be deformed behind the passenger cylinder head because the stock engine mounts held the engine too far aft for that "little" engine bay, and if the engine/trans was any farther up it would need a custom driveshaft.
...been there, done that. Don't want complicated, lol.