I wonder how much work it would take to install this on a TJ?
Don't think you can use this on a TJ without a lot of work. The JK bar attaches under the frame while the TJ bar attaches above the frame. This does work perfect for YJs and probably work for XJs and ZJs too.
When the JK first came out, these bars were mis-listed as around $130, a lot of Jeep guys bought em up and modified them to work. Check out JF for some writeups.