Your photo did not come up, but here's what I know...
Your front driveshaft has a CV joint where it attaches to the transfer case. If the boot is ripped the CV joint will soon be destroyed. There is a repair kit offered by Dorman. It replaces the CV joint and the boot. I've installed this kit (in a '00 Mountaineer AWD) and it's not terribly hard to do. I paid around $90 for the kit. I found a YouTube video that takes you through the process that was quite helpful. You can also purchase a rebuilt driveshaft ready to install for about twice the cost. I also had to purchase a CV boot band installation tool and good quality torx socket for the driveshaft yoke bolts. BTW the bolts that come with the kit are too short, so you will need to reuse your old bolts.
As far as I was able to determine, Dorman is the only one offering a rebuild kit, so I suspect any rebuilt shaft will have the Dorman parts. Some here have had trouble with the boot in the Dorman kit not lasting very long. Mine is still okay after about 2.5 years. I don't see the Dorman kit offered on eBay right now, but many of the kits have the same part number as the Dorman part, 932-001 (hmmm).
Here's an example of a kit and what's included. Apparently prices have dropped based on what I'm now seeing on eBay.
http://www.ebay.com/itm/Front-Drive-Shaft-Rear-CV-Joint-Boot-Repair-Kit-For-Ford-Pickup-Truck-4WD-4x4-/262809724706?fits=Year:1999|Model:Explorer&hash=item3d30ae2722:g:wx8AAOSwGotWnEvi&vxp=mtr