xyellow,
There are differing opinions on what you are looking for. When I looked for my axle I wanted the whole thing. That way I would know I had every part. The following is a list of parts I replaced.

1. Calipers, for $36 brand new fully loaded with pads and bolts I felt it was worth it, and not worth the risk of having a 26 year old part fail.
2. Gears, I wanted 5:13's
3. Steering. The Calmini kit comes with what you need to use the stock steering, but again I did not want to use and old part. Plus I wanted something stronger that stock.
4. Locking Hubs. Happened to be the one thing I did not get with the axle.
5. Diff cover. Just wanted a stronger one, but you could also just get a diff guard.

If I had it to do again, I would still look for a complete axle.
Hope that helps. As for the gearing question, my preferance was 5:13's for 35 inch tires. Even with these gears I still have problems climbing steap hills on the freeway. Others have said the next gear lower is the best choice. I just don't see how. My truck stock weighed 5400 lbs. Now I would have to guess closer to 6000 or even higher. I need the extra gearing just to pull the weight of the truck (and with the trailer as well)

Hope that helps.

Casper