Here is a link to my build thread. Jeep TJ and a 4bt diesel
I will say that site has by far the most info on diesel swaps I have ever seen. As with all internet sites you need to weed out the BS from facts, from opinions based on poor foundation.
There are some basic questions you need to ask yourself, and some info I would be happy to give you before you start.
First this is not a cheap swap. You will not save enough fuel to recover the cost within a reasonable timeframe. I used a Cummins 4bt (it is not called a BT4) and this engine will rarely give you 20mpg+. mid teens is more realistic. My Jeep is built for off road only so i didn't care about mileage. Look around the 4btswaps site for other Jeep swaps there are many. Do not worry so much about finding a YJ specific swap CJ,YJ,TJ are all close enough for all intents and purposes here.
List the reasons you want to do a diesel swap.
List what your expectations are.
How much do you have to spend?
What is your planned use for this Jeep?
Auto or manual trans?
Can you weld and fabricate?
Are you used to diesels and all their idiosyncrasies?