I've done 1 , sold my original 4.0 to a local with an 02 Tremor. He had to pickup a fuel system and have his ecm flashed by Ford ( if you have a whole donar truck.. you wont have to do such ).
Its not THAT hard, have friends and some beer. Make sure the friends don't sit around guarding the beer though
. Took us a total of .. 6 hours.. 4 people whom knew what they were doing ( all ranger owners ). Everything was CLEAN, nothing in the way.