I have heard it's not a good idea to run a 5" lift with out long arms. Currently I have the Rough Country 4-6" short LCAs on. Any thoughts? thanks

You can, I ran a 5.5" on short arms no problem, your flex will be limited though, and your front axle will be pushed back a little bit, causing the castor to be all jacked up...I ran mine for a year and a half and really saw no negatives except for the flex, it rides a little rougher too. I installed drop brackets a couple of months ago, it's much better, but they have issues of their own as well..

I have a Rustys 6.5 short arm with adjustable upper control arms. Its perfect, but i will go long arm someday when i lift it even more

Can I keep the stock uppers or do I need longer? thanks

Not sure the good they about having adjustable uppers was being able to shortin them for better caster

No way! The stock uppers are not even good for 4 inches really. I'm guessing your xj has a bad ride as it sits. It's because the uppers are a a steep angle with that much lift. And it pulls the axle back. It puts stuff in a bind. You will need at min. Adjustable uppers. But u really need both.

You can run the RC control arm drop brackets to regain some flex and ride quality.

i would get adjustable uppers and lowers or atleast some longer fixed uppers and lowers. then eventually get drop brackets or longarms