1994 4x4 Question

I recently replaced my front diff with a used one. We'll the problem now is when i am in 4x4 it makes this really loud "CLUNK" and i dont know why. I have drive the truck both on and off road to test it out " just driven no beating on it " and offroad is where it seems to do it most but only in 4x4. Earlyer today i had the truck in 4x4 and tryed to pull out of my driveway, while turning the wheel to the right it made that same "CLUNKING" sound and i was told that my Cv Shafts are bad and i would need to replace them. Is there anything else that might be wrong with it ? Or could it not be the Cv Shafts and somthing entierly different, Please any and all help is needed and would be greatly appreciated.

CV Joints usually don't wear out. Look at the boots, see if they are ripped. If they are they would have thrown all of the grease out and now they are getting grime in them and it is chewing up the bearings, causing a clunk.

When we replaced the front diff we checked on them and they were fine, prior to replacing it , the truck also made this noise but like i said only seems to be doing it while in gravel or in snow which is where i first noticed the problem.