[dirty4man]

it can be done with the swing arm on or off. It is easier to do with the swing arm/rearend off as a complete unit. You will need a 17mm allen socket, the spanner wrench is not needed to take it apart. when putting it back together you can use a hammer and punch to lock down the spanner nut. If the swing arm bearings need to be changed, they can be a pain sometimes.
If you remove the swing arm and rear end as a unit, the only thing that needs to be removed is the brake cables, swing arm boot of course and the vent lines on the brakes and diff. Its not to bad of a job.

Did the ujoint break? if so the swing arm will need to be removed anyway so the output shaft can be checked to make sure it isn't bent.

 

[dirty4man]

If your waiting on it to break, more than likely the output shalf will be bent as well if it ever happens. I haven't compaired the two either, so I'am not for sure on the difference.

to just change out the u-joint you can remove the rearend from the swingarm and slid the new u-joint up the tube with the driveshalf. you will just have to undo the boot to help align it on the output shalf. it is alittle tricky, but I have done it many times.