BMW has a 320d out here now don't they? Or a 328d? Something like that. What they should have done from the beginning. 335d was a great car, 430ish TQ, more than an M5. But they all showed up allocated to dealers loaded up with options, and it was the biggest most powerful diesel BMW had in a I6. So they were close to $60,000 and thirsty, they didn't crack 40mpg did they?
On the old school front, it turns out Mercedes sold a decent number of W124 4matic diesels. 2.5L 5cyls and 3.0L 6cyls. Turbo and non. So a front oil pan for a 602 or 603 diesel with the provisions for the front diff exists. The question is getting a 717.4XX 5speed between the motor and the transfer case. I'm still thinging about the feasability of this. I don't have the skills necessary to come up with a way to connect the transfer case to the back of the manual. I've been keeping my eye out of a 4matic in the junkyard so I could snag some bits to at least think about this.
Early Euro-Spec G wagons with manual transmissions used a standard manual gearbox with a short shaft to the transfer case which was mounted solid in the center of the frame. 4, 5, and 6 cyl engines sit different amounts forward and backward in the engine bay, so the length of the transfer case to gearbox shaft varied with the motor. They are not all that big, but I don't think fitting a 2 range transfer case under an E class is feasable. But if it were it would make the transfercase full mechanical, the 4matic used a viscous coupling like mid 90s Jeeps (thanks magna steyr).
I don't know if Steven and Will are stilling thinking this through, but it was a good time killer at the office to consider it.
Yes the 4matic 1 system uses a really wacky front coil spring with one elongated coil to clear the front axle.
![Image](http://www.mercedesclass.net/wp-content/uploads/2011/10/87F1.jpg)
![Image](http://www.mbpartsworld.com/images/parts/mb/fullsize/B27135000001.950626.jpg)
This adapter replaces the tailhousing on the 722.3 automatic transmission and bolts to the transfer case on the other side
![Image](http://www.mbpartsworld.com/images/parts/mb/fullsize/B26575000003.950915.jpg)