You can replace the joint but by the time you go to all the trouble, for just a little more you can get the axle and it's so much less of a hassle to do the whole thing. fcpgroton.com and raxles.com has them for the best prices I've seen.
I replaced my 2nd axel shaft about a month ago on my S70 GLT. That was what caused me to sell the car. Only 148k but didn't want the thing to start nickle and diming me to death aka like a car payment. I would rec. doing the whole axel shaft. I was able to get a used one at a local volvo bone yard for $150<p>Good luck. I feel your pain <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/frown.gif" BORDER="0">