Any time my front auto hubs have acted up it was always a broken HUB in one way or another,but today while going down my creek it acted up so I pulled both hubs and they both appear to be fine yet there is still a GRINDING sound while engaged and no 4x4 so I spun my axle were the two pieces meet ( rubber boot ) and if I grab the left side of the boot and turn with my hand it spins on the right side of the rubber boot, I can hold the right side of the boot and turn the left side ANYWAYS I have never messed with this piece before so I took a quick picture to get my point across, is there something INSIDE this rubber boot that BUSTED?

 

Just the boot or the actual shafts spin?

 

I can hold the shaft to the left of the boot and grab the shaft right of the boot and they spin on each other in either direction,the boot does NOT turn or spin. Does that make sense?

The right / smaller shaft spins INSIDE of the boot while the boot does not move,all while I hold the left shaft.

 

Yeah it sounds like something is broken internally. I'm not sure what that parts is called. Maybe it is just some sort of slip joint.

 

yea its a slip joint