After rebuilding my engine...took some time due to the crazy cost of rebuilding a 5.9 magnum my front axle stripped out the first time I needed to use my 4x4. It turns out that this is a common problem in theses trucks. The front differential has 2 short splined shafts called stub shafts that the cv axles plug into. The female splines tend to rust out on the cv shafts and chew up the soft metal of the stubs shafts in the process.
This is how I fix my problem for about $2
Step 1: Pull the cv and stub shafts
The cv axles are held on by a c-clip a good tug or a pry with a long screw driver should pop them off of the stub shafts.
Don't pull on the end of the axle, you will rip the boots or damage the cv and turn your $2.00 fix into a $200.00 fix quick.
Pull from the end closest to the differential.
Now you can see the stub shafts where they enter the diff.
These are also held in by C-Clips but are a PTA to get out. If you have a slide hammer big enough use it. If not try to pry them out with a large flat head. My slide hammer was not big enough and flat heat did not work. I pulled the cover off the front "needed a cleaning any way" and used a large screw driver to pry between the pinon gear pin and the stub.
The passenger side is long and drivers side is short.