This question comes up every couple of months or so, but I'm always more than happy to answer any questions on the swap.
Getting the engine is the hardest part of the swap because these engines have become so popular in the last few years. It seems that everybody wants one. There are even sites out there that show you how to install these engines in Furds and Chebbys. (I wish they keep to their own engines!) I can tell you that I almost gave up on the idea because it took me over a year to find a suitable donor
Getting a donor truck is the best way to do this because you can get everything you need but don't hold your breath for a wreck, these trucks seem to sell as soon as the wreck occurs. If you want this bad enough don't be afraid of taking a perfectly good truck to use as a donor and expect to pay the high market value for a Cummins powered Dodge (You can always take your gas engine and swap it into the donor and sell it later to recoup some of your expense)
Once you find the engine, it all bolts in easily, there are no additional parts you will need to do the swap, but you will need the tranny and if you can't find a 4wd donor, expect to do a tail shaft conversion to mount your transfer case to the donor tranny or do what I'm doing and go with a divorced t-case.
You can see what I've done on my site at;
www.rxt.ramchargercentral.net
Ed