The easiest way to look at it is two streams if you will... GenI's and GenII's with the 3.0L V6 were roughly equivalent, axle/trans etc to the 2.5L 4D56TDi diesels. The trucks that got the 3.5 V6, along with larger running gear, trans etc, also got the 2.8L 4M40TDi diesels. Also keep in mind when looking at JDM stuff, that Japan was generally a year ahead of the rest of the world (ROW). So my GenII Pajero shorty was a 1991, but the ROW didn't see a genII till 92. My 93 4M40 has the larger running gear same as the 3.5's, but they weren't available in the ROW till 94.

Hope this helps establish some bases for you.

If you're going to all that effort, don't neglect the gearing. Many think of a diesel swap but stop at the engine. All the diesels had deeper diff gears. My 4D had 488s and my 4M has 490s. IMHO the diesels need them, esp on bigger than stock tires. Also, the 4D gets better fuel economy, but you pay for it somewhat in terms of harder starts and a more "agricultural" feel (dunno how else to describe it), compared to the 4M40 which is almost as smooth as my 3.0L V6 was. Not to mention less power...