In short - It's easier on a 2wd than a 4wd AND there is two different versions - one for 2 door and one for 4 door and they are VEHICLE SPECIFIC.
I had a mechanic with a lift swap mine bad rack out and he said it was a big difference in labor with the 4wd vs a 2wd Explorer.
He said that you could do a 2wd in your driveway/garage no problem, but the 4wd was a whole 'nuther animal altogether...
After paying for the steering rack repair, as well as swapping out the power steering pump, I now run an inline power steering filter on the return line from the factory stock power steering fluid cooler. I replace the inline filter every 10,000 - 12,000 miles. You can unscrew the housing and see what is captured in it - and it's an eye opener. Now my power steering fluid is red and clear running the filter - not a "red/black" color that is typically seen when not running a filter.
Here's what I use as well as who I buy it from:
http://www.ebay.com/itm/Magnefine-3...pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr
I also change my P/S fluid every 12,000 miles now - cheaper than that steering rack repair. I run Mobile 1 Synthetic AFT fluid or Redline Synthetic Power Steering fluid - interchanging between the two because of availability (or lack of). I use a Harbor Freight Vacuum Pump to get the air out of the system after draining and then refilling. I drain the system by just pulling one of the rubber lines on the factory stock P/S Fluid Cooler (lower line I believe). When done draining, I replace the P/S fluid with new P/S fluid. BUT - NOW there is air in the P/S System lines that must be taken out.
http://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-92474.html
Power Steering Pump Fitting for Vacuum Tool: I purchased a tapered rubber stopper from ace hardware and pushed a brass nipple that's "barbed" and has a hole through it, and pierce it through the center of the rubber stopper. The vacuum tool is hooked up to the exposed nipple via a rubber air line, and I place the tapered end of the rubber stopper in the P/S Pump. I pump up it up to around "10 inches" on the vacuum gauge, start my ex, and turn the wheel from side to side. As vacuum is pulling out air from the system, you will see the gauge lower in numerical value. Then I top off/add p/s fluid to the proper operating level, and I'm done ;-)