I pulled a steering box out of my parts van (91 van) and put it into our '92 explorer.. It was hard.. The hardest part was removing the pitman arm.. the pitman arm puller I had didn't really fit around the pitman arm (I had a superlift drop pitman arm on the explorer already)..
Other than the steering box being heavy, and having to hold it up (truck is lifted) until I got a bolt in, it wasn't hard.. I just undid the lines and steering shaft and disconnected the pitman from the tie rod, and dropped the box.. I took the pitman arm off on the ground (didn't really have enough room to do that on the truck).
~Mark