Steering shaft removal/replacement

- 1990 XJ, Power steering, AW4. The U-joints on the steering shaft are done for. So I purchased a replacement. I have a couple of questions about removal/replacement. Do I have to unbolt/remove the steering box ? The new shaft is the same length as the installed old shaft. I do not see a way to remove the old shaft without moving the steering box forward. I have seen some comments that the shaft is collapsible. Neither the new shaft nor the old one appear to collapse. I see where it could slide but I assume it is engineered to only collapse in a crash. Unbolting the steering gear is not a problem, however I need to plan that into the replacement time. If so I am guessing I need to pull the Pitman arm also. Any insight provided would be appreciated .

Thanks

Just wondering - are the U-joints replaceable ?

I am not sure about a 90 XJ but on my 01 XJ the shaft that connects to the steering box end slides inside the shaft that connects to the steering wheel end. Normally at the steering box end there is a splined couple joint where you just remove a single bolt then you pull the the whole u-joint assembly off. You may need to use a pry bar to get it moving. You repeat this same process for the steering wheel end which has a similar splined u-joint assembly held by one bolt. At the steering wheel end you may need to remove some interior plastic cowling/panels to access the joint. You shouldn't need to remove the steering gearbox at least on the 01.
I think many years ago it was possible to get replacement u-joints but I don't think they are available now and it is easier and probably less expensive to get a complete replacement assembly.