The Mitsubishi DR6 is actually a motor that is almost identical to a 2H factory diesel from a Land Cruiser. They have roughly the same power output, both come naturally aspirated, are I-6 motors and even have a ton of the same looking parts.  
This engine was Royal Rose's first diesel conversion - he bought it from Mudrak after some idiot scrapped it to put in a V8!, and it was even already in a Land Cruiser FJ40! 

The engine lasted some 5 or 6 months before it developed cracks in the head which forced Royal to install a Cummins 6AT.  The 6DR was actually a rare but factory option for full size Dodge trucks from the late 70s and early 80s.  In the pictures below you'll see a RaJay turbo that I actually bought off Royal which we installed on my HJ60.  If you want a diesel engine this isn't a bad choice either though after owning a turbocharged diesel I don't think I'll ever go back.  But then again I live at 6000 feet and a turbo up here makes a world of difference whereas I thought my HJ60 was full of power before the altitutude change.  You might want to see this page on diesels and altitude.

These photos are also courtesy of Ken Dahlberg, see a listing of all of his diesel engine picts here.

Click on each picture for a full size image