How to diagnose the transfer case?

updated recap on the problem: when taking off under mod. to hvy power i get a sound from undernearth that sounds like something is stripping. i have described this as a clicking sound which is why i feel that many people have suggested that the uv joints could be bad. it is not a clicking as would be heard on cv axles in a ft wheel drive. think of maybe like a zip wire for wiring. what it sounds like if you pull it tight really fast. kinda like that but naturally a lot lounder. i can feel it sometimes from underneath my seat. and sometimes it seems as if it is coming from the front wheel. also while driving straight down the hwy. it does not make the strip or click sound but does make a knock or thump mostly between 30-45. i have checked the axles all ok. is there a way do diagnose the transfer case. can i unbolt the front shaft to test it in the drive way to see if it still makes the sound. can the chain be replaced with out complete removal of the transfer case. what are the steps