So my left front wheel U joint is shot. Can I do it simply by removing the axle, replacing the joint, and sliding the axle back in, WITHOUT going into the diff at all? I guess I'm asking if my axle seal will get damaged during re-assembly. It doesn't leak at all right now.

 

If you are careful, you can do it without trashing the seal.

 

i did both driver side and passenger side u joints on my truck a few months ago. i never went into the diff. and i have had no problems with leaks. just be a bit carefull.

 

Good to hear. Makes the job much easier. Will be doing it next week.

 

Same here. Then again 2 weeks ago to do balljoints.

 

treat the axle seal like glass when reinserting the axle.

the hardest part can be removal of the big axle nut 1-11/16 and the removal of the hub bearing from the knuckle.

here's some nice write ups.
http://www.pavementsucks.com/tech-article-5.htm
http://www.pavementsucks.com/tech-article-3.htm

precision brand makes some very heavy replacements.