My truck has had a vibration since I bought it. Even after I had the transfer case rebuilt this summer it persisted. Two transmission shops told me it was the driveshaft even when I suggested it was the mainshaft and told them I had the dirveshaft checked for balance by a reputable shop. Well, I replaced it yesterday and no more vibrations! The whole job took about 8 1/2 hours. I had help from a neighbor for most of it. It feels good to be right. It used to take ten minutes with a hammer to get the slip yoke out of the back of the transfer case. When my friend put it on it took about two seconds.