rather than reinvent the thread from hades just scroll down to the thread
titled "gas to diesel changover" started on 12/10/2007.
michael

Sure it can be done but it is not going to be cheap or easy.  Basically, you
will need a donor vehicle (with a good drive train) to supply you with all
of the parts required (and you will still have to buy some new anyway), the
space to work on both trucks, the tools needed to remove the engines,
transmissions, fuel tank, AC system, ect..  On top of that you will need
another vehicle to use while you are performing the swap as this is not a
one day thing and most importantly, you need to do a truthful evaluation of
your own skills and tools to be sure that you can so this kind of work and
that you have some friends that can take the time to help you when you need
it because at times, you will need it.

If you are thinking of just buying the engine, you would be in for a big
supprise as that would simply not work.  The parts required would be the
engine, trans, exhaust, intercoller and intake plumbing, turbo, computer,
front wiring harness, under dash harness, IIRC, the instrument cluster is
different, modifications to the brake and fuel systems, front springs, dual
batteries and hardware, and these are just the major components I can think
of off hand.  While not impossible and that many of these compononts can be
had from an intact donor vehicle, as you can see there is a lot of work
involved in this swap.  Another thing to think about is the registration and
title of your to be modified vehicle.  If your vehicle currently requires
emissions testing where you live, this could become a problem when you
change to a diesel and you need to find out exactly what your options are.
Just something to think about and resolve before you get in the middle of
doing the work.

Another option might be to see what the price is for a used one around the
same year as yours.  You are going to have to look anyway for the donor
vehicle to modify yours so there really isn't much more work involved.  It
is much easier to fix up an existing vehicle then it is to seriously modify
one and then you can sell your other one to recoup some of the costs.  Eiter
way, if you decide to get one and fix it up or modify yours, this is a good
place to get the answers to your questions about what needs to be done.  We
have a few in here that really know their stuff when it comes to both the 12
and 24 valve versions of the diesel engine.  Good luck.