The ZJ stuff is a big improvement for the price, can reuse your existing drag link and only have to buy the tie rod parts. With the XJ drag link and the ZJ V8 tie rod you have 22mm threads at the adjusters, which are nearly 7/8" shank (same as one ton ends). But the balls in the joints will wear out pretty quick with abuse.
The classical "one ton" setups switch to a simpler style that is easier to produce. Most of these guys use off the shelf joints so they all have the same problem. First is you sometimes have to ream the knuckles for larger tapers, stock knuckles don't have a lot of excess meat on them either. Second is the joint between the tie rod and drag link wears out quickly, allowing the joint to "roll" before the rods get pushed, resulting in a dead spot in the steering. That's what "the cure" piece fixes, puts some preload back on that joint so that there is less slop (roll).
Currie uses a special joint with the drag link that is thicker on the sides, prevents lateral wear (ie prevents the "roll" from developing). The ends are also custom, one ton shanks with stock tapering, so you don't have to do any mods to the knuckles. Its expensive but its drop-in compatible, holds up well, and doesn't develop the slop / roll that typical one ton systems develop. Its weakness is the small tapers, I suppose.
Synergy is trying to play in the same space as Currie but the reviews I read say they do not have a reinforced TRE at the joint, so they also develop roll. Don't know if they fixed it.
Iron Man 4x4 has come out with a kit too, stock style but it uses heavier off-the-shelf TREs that require reaming. They have some issues with tire size as well because of the larger ends. I don't think he's doing anything about the juncture joint either, so may have problems with roll as well.
WJ steering changes everything so there is a big up-front cost, but it puts you the furthest down the field with crossover steering that doesn't have any of these problems.
I ran the ZJ for years with 31s and 32s, upgraded to the Currectlync when I went to 35s (ZJ joints were blown out and gave me DW with the added tire weight and imbalance). I plan to upgrade to Reid knuckles and crossover steering then.
