One will definitely know when the DSB is bad. The symptoms are the loud intermittent squeeling, problems with shifting and vibrations at the center console. I had mine replaced this week for a grand total of $1334, I requested the dealership to give me the old drive shaft and they obliged. First of all you cannot order just the bearing you have to replace the whole entire shaft. Other vehicles use the same bearing, it is a pressed on bearing, to get it off you would have to cut the drive shaft, and have it re welded back on with a lathe, this is a costly procedure.
You can also buy one from Racks and Axles out of Indianapolis, IN. for $600 plus $100 core + s/h. The dealerships are charging around $1100 plus labor.
Our dealership told us that if we had found the shaft, they would install it for us, a little too late for us unfortunately, but hopefully someone reads this and does their homework before shelling out 1400 bucks!
****WARNING**** the drive shaft must be properly aligned or the problem will re occur quickly...