One problem related to transfer case has been reported for the 2001 Chevrolet 2500. The most recently reported issues are listed below.
Brake line failure. Abs system failure. Light for abs and brake have been on and off since original purchase. Dealers could not eliminate the problem. Noticed rust on brake lines throughout. Currently all brake lines are covered in rust and leaking just prior to the abs components on driver side middle frame rail. Brake lines are brittle to the touch. Currently the breaking system has no pressure. All fluid has leaked from the system. Service requested by dealer for noisy and leaking transfer case. Dealer applied grease to the drive shaft. Problem not resolved. While driving in 4 wheel drive, the transfer case experienced a catastrophic failure. Unit was extremely hot and the gears were ground out. To my knowledge gm is and was aware that the transfer case fluid pumps were wearing a hole in the case from the inside. Now know as "pump rub". Dealers had opportunities to repair and or replace and failed to act to resolve the known damage.