Try searching this forum on the following and visit their websites. Lots of info on XOC...depends on how much you want to spend as well. I went the somewhat cheaper route and pieced it together how I wanted it.

1. http://www.purenissan.com/xterra.htm
2. http://www.extreme4x4parts.com
3. http://www.spencerlowracing.com
4. http://www.4x4parts.com/

I have #4 (above) front a-arm/balljoint lift along with #2 Add-a-Leafs & torsion bars, and #3's 2" shackles. So far so good.