Another vote for 4.88s. I run them with 33s (km2 to be exact) and love it. Plenty of power and grunt, awesome in 4low in the rocks and trails, and pretty good MPG for a lifted heavy brick.
Before I regeared I went and test drove a few xjs....
- 4.56 and 33s : Not to bad felt just about "right" could of used more power on hills as it wanted to downshift still
- 4.56 and 35s: Def undergeared, needed more gear
I figured since both could of used a bit more power 4.88s was the answer. I was worried about gear strength and whatnot but honestly the difference between 4.56 and 4.88 is minimal in a dana 30, there both small. I run an aussie up front and a no slip in the rear and its awesome, I usually average around 15 mpg mixed driving and have gotten 20 mpg hand calculated with a corrected speedo on long highway trips.
Don't fear the gear man, your gona love 4.88s.