Its a dam hard graft did mine a few weeks ago put 200 tdi in, basically bought a rotten disco stipped it of its engine gearbox rad&intercooler got to change engine mounts on chassis as there different, the wiring loom in the engine bay for the engine, swirl pot in the fuel tank, fuel lines, etc, etc
if you are going to do it i would buy a rotten or damaged disco as there is lots of little thing different hope this helps