(01' 4x4 auto tranny). I have this clunking sound all the sudden that I cant figure out. Its like U joints going bad and it happens when I accelerate and brake. Got under the truck and tried to move the rear drive shaft around and it felt solid. Went to feel the front and I could rotate the drive shaft about 3/4 inch back and forth. The movement isnt in the U-joints,its like there is a little slack. Is this normal ?

 

It's normal. What you should try doing is lubing that rear driveshaft near the splines. Unbolt the four little bolts at the axle end and pull it apart from the transfer case. Shove grease in the shaft and on the splines. It could be your rear driveshaft dried up. They clunk when you start going and when you come to a stop.