4x4 Clunkin

[socalexlorer]

I am looking for some help fellas. I have a 94 Explorer w/ 100K miles and automatic locking hubs. When I engage 4-wheel drive and begin moving after about 40- 50 ft I hear a horrendous clunk that can be felt through the floorboard. It repeats itself w/ out any apparent pattern. Reading the various responses on previous posts I though it was the hubs. Last weekend I took them apart expecting to find a broken plastic cam- however this was not the case. Everything was fine less some grease that had been jelled. I disassembled the hubs washed and greased them. I am approaching the weekend and I need to begin trouble shooting something else- u-joints? How would I know? Ball Joints? How would I know? I am getting bummed out because the weather is great and I haven’t been able to go offroad.

Thanks for the help.

4x4 Blues
Rico