You want the whole front differential and axle housing? Try
www.car-part.com and find one in a junkyard close to you, if you want to go that route. (should run around $130 or so)
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EDIT: The name of the item for car-part purposes is "carrier (see also differential)"
To remove the entire front axle assembly:
Jack up the truck, put on jackstands so the front is in the air
Take front tires off
Have someone hold the brake, loosen axle nut on both sides
remove brakes and hardware, hang calipers from a piece of wire, dont use the hose for hanging purposes
Remove the "thru bolt" from upper control arm
Seperate upper control arm from steering knuckle
Remove cotter pin and remove the nut on the tierod, remove tierod from steering knuckle
Remove the cotter pin from lower balljoint, loosen nut almost to the point of taking it off
hit the steering knuckle right around the area of lower balljoint, knuckle should drop down to the balljoint nut, remove it and knuckle while pushing the CV inwards
Use a long screwdriver, insert screwdriver between the inner CV flange and the front differential and pry it out, it will come out easily if this is done properly. Diff fluid will come out of the open end of the diff/axle assembly. Don't worry about that, is junk anyway
Repeat the above steps for the other side. I took out whatever front diff cover bolts i could and inserted a screwdriver to make some space to drain the diff fluid.
Climb under the truck, there are 3 mounting points (edit, or are there only 2?hmmm) for the entire front axle assembly, remove the nuts and bolts (the nut end has a "keeper" of sorts on it to help).
The whole assembly is about 60lbs. (im guessing) so be aware of that, its not overly heavy, just awkward.
Replacement is reverse of extraction.
Before you replace the front differential and assembly (if going with the junkyard one) make sure you can remove the fill plug (wont do much good to hang it under the truck if you cant fill it) replace the axle seals (easy job now, really sucks when installed) and take a good hard look at the outer axle bearings that the CV shaft ride on (again, a heck of alot easier to do this now with the assembly out of the truck). This is where it may be best to rebuild yours, but that decision is yours and should depend on why you are thinking of replacing the entire assembly.
Does this answer your question?
There are also some members that have the assembly for sale, check the "auto parts for sale" area