Please post this on the Diesel forum, you'll get a lot more responses.
Anyway, If your oil consumption is 1000 miles per quart or worse, ummm, get prepared for bad news. The 3.5L engine was flawed from the factory and smoking is one of the early signs of failure, followed by lack of power, abnormal noise, and very high oil consumption...
This link has more info (server seems down at the moment, though.)
http://www.mbz.org/info/complaints/350SD/
If you can't open the above link, try this link to the same article in Google's cache:
http://tinyurl.com/5h5x8
