Volvo Repair: drive shaft trouble, universal joints, drive shaft

Question
I have noticed a little vibration from the universal joints during acceleration, but nothing too major. Recently the drive shaft rumbles alot, when I slow down to stop.  It's pretty bad. Should I plan on changing the universal joints, or is there another possible source I should consider?  It feels/sounds like the problem is near the transmission area.   
Thanks again.

Answer
Sean, most likely it is the u-joints but it can also be the center bearing and cushion.  You can test the ujoints by taking the shaft down and moving the u-joints left and right and up and down.  Should move freely.  If they bind, replace all of them.  Roger