Just changed the rack n pinion on my LS a couple of weeks ago. If it is the rack, its not a hard job at all and depending on how many times the system has gone bone dry it may be worth your time to change the PS pump also which is even easier.
Also, rack n pinions are known to have leaks through the seals and pressure lines. So depending on how many miles you have(if its a lot) it'll probably be well more worth it to just change the whole rack since you would have to take it out anyway(most likely you would have to in the case that you did wanna just change the seals opposed to spending the money on a whole new rack)
Whatever it is just make sure you keep PS fluid in it and don't let it go dry.
