what is this clicking noise?

I have a 1984 jeep cherokee witha 2.8liter v6. when I lock it in 4x4 it makes a clicking noise. Ive changed all the u-joints, and rebulilt the cv joint on the front drive shaft, could this be a bad bearing in the t-case or could it be the front hubs. Its hard to tell wear the sound is coming from. Please help I need to get this thing back wheelin!

seems to me that if your running the automotive style cv at the tcase they click alot on lifted xj's...IIRC...we swaped a new seal and later model yoke on the wifes 86 xj tcase so we could run the ujoint type constant velocity...