Transfer case noise when truck is at idle

SOURCE: my 1990 chevy is making a clicking noise around the transfer case

Is it louder when it is Cold?

SOURCE: transfer case making roaring rattling sound

it's possible you might need to just change the trans case fluid.... it's a pretty simple task, i usually do all the small minor work first before i take it to a dealer to fix.... if they said you need a new trans case, but didn't tell you why, more than likely there might be something you could do yourself to make it better... those service men have been working around vehicles long enough, they should be able to tell you exactly what's wrong!
i would also do a tranny fluid change to... some of the noise could be coming from there too -- when you change either fluid, add a little lucas transmission fluid stabilizer, it helps alot with seals and makes the fluid stick to the gears better...

SOURCE: 2003 Chevy Silverado Transfer Case

well make sure it is the tranfercase because if it was u wouldent have 4wd and u wouldent be able to drive it but it would be cheper to rebuild it but make sure first because some people are just out for your money good luck

SOURCE: Idle Problem when you slow down of come to a stop idle goes low

THis has happened to me in the past. My fix was to clean the throttle body. The problem began after my battery died. The computer was defaulted back to its original settings after replacing the battery. Once I cleaned the throttle body, everything was fine. This happened at about 85,000 miles.

SOURCE: transfer case clunk 2000 chevy silverado 1500 4x4

One thing to check, which is often the culprit in these situations is the U-joints. With the truck off, crawl under the vehicle and grab hold of the shaft leading into as well as the shaft going out of your transfer case, If htere is a lot of "slop in it, chance are it is in need of repair. Also I would check the oil level in the transfer case, in an attempt not to challenge you intelligence, there should be a plug located in the lower part about 2 inches from the bottom or so. it usually has a square hole that a 1/2" ratchet fits into. Pull the plug, and stick your pinky into the hole, you should be able to feel the lubricant just below the hole, if not it is in dire need of a filling. also check for metallic remnants in the fluid. this is a sign that things are not as they should be. In that case contact a repairman for a more thorough look.