I just had the transmission worked on as the planetary and sun gears needed replaced. Two days later, the service 4wd light came on and I noticed a loud rattling noise coming from the rear drive shaft area while driving and a whining noise while in park. At first I thought a worn u-joint but they were good. Could this be a transfer case issue?

2000 Chevy Silverado 4x4, 5.3L V8, 204,000 miles

 

anyone?