This picture was stolen from Morgan Fletcher's web site about Toyota Land Cruisers (and FJ55s).  Click here to see his web site, click here to see the section of his site that I stole this from.

This truck belongs to Alan Lungi of Rock Buggy Supply.  It is powered by a Cummins 4BT (the most modern version) tweaked to over 750 ft/lbs of torque(!) with the Bosch P1700 inline injection pump.  The rest of truck seen above is somewhat of a FJ55 hybrid.  As you can see it has a custom tube frame.  It also runs on 44" tires, 1 ton axles, and hydraulic coilover shocks.  It also has a SM465 transmission.

I spoke to Alan a few days ago as I'm now considering a 4BT into a FJ55 but as a fully functional daily driver.  He says he thinks it's a bad idea, the engine is slow, puts out too much torque for a Toyota drive train and would be a poor daily driver.  But I can possibly get the engine for free and I'm looking into trading a web site for a fairly straight and minimally rusted FJ55 with a blown engine so I might just finally get my chance to build a custom diesel powered Cruiser.

Alan says it is so loud and rattly that he has to yell to talk to the person next to him and that it's so torquey that he can plant the front tires against a minorly inverted wall and it will drive up it.  Pretty sweet!