So over the past few weeks I was hearing a clattering sound in my driveline as it increases with speed. I have an 01 Sierra 4x4. I took out the front cv shafts, front driveshaft, and replaced both rear driveshaft u joints as well as front hubs from a 2wd. Noise still didn't go away. I was taking a road trip and about two hours down the road I heard a loud bang and smoke coming out the back of the truck. Pull over, and see rear u joint broken. I start pulling out my tools then I notice the entire transfer case has broken next to the transmission mount, making it rotate down and pour fluid all over the place. My question is, what would have caused this? Chain rubbing against the case or that little clip that seems to always break?

 

 

Woah, that looks nasty.