I had some used rustys lowers on my rig for a while when I got it, and coils. I gave them away for free when I upgraded to TNT long arms. I would say go with Rustys if its free or almost free. dont pay full price for it. I ran it for years, was so much happier when I ended up going with TNT long arms and some used RE 5.5" coils.
I still run my rustys rear leaves, but with 4 stock XJ leaves added to help with all the weight in the rear. and the fact the leaves are around 9 years old this point and have been wheeled hard. they were on the rig when I got it though. But I didnt pay for it. I would happily run a free 3" lift of Rustys as long as it was free.
ive sold lots of rustys steering and long arms, and short arms off numerous rigs over the years. The NON-cross over steering seems to be crappy, the trackbars seem like terribly unsafe cheap junk and dangerous, the 2 Ive seen in person on a rig I drove for a short time before parting. The HD cross steering Ive seen was decently beefy and I would run it if It was under 200$ shipped.
I go ruffstuff for steering , link parts, rrod ends, etc etc these days.
there is a reason rustys parts sell for next to nothing or go free used when when other brands like say rubicon express and TNT and other decent brand still hold a decent value used. most long arm kits sell fast for close to full price. The 2 rustys long arms sets ive sold used went for like 300-350$.
if youre spending money on new parts, do more research, and you will probably end up going another route.