Two problems related to driveshaft have been reported for the 2003 GMC C2500. The most recently reported issues are listed below.
2003 GMC sierra 3/4 ton, 8. 1 litre engine with allison transmission-gm says they are aware there is a problem with the driveshaft where it goes in to the rear end. Every 10,000 to 15,000 miles it must be removed and cleaned, greased and replaced. They are unwilling to place this on a recall list and say in the future it will be a maintenance item and it will be done at the owners expense every 2 or 3 oil changes. As for mine they will do it for a short time longer and then it will be my problem-this is a definite defect they acknowledge but refuse to do anything with these vehicles that already have this problem, if you are already out of original warranty and did not purchase the extended warranty you will just have to pay out of your own pocket,them knowing fully about the problem.
There was an electrical short in the transfer case that resulted in vehicle engaging into 2-wheel drive or 4-wheel drive by itself. Dealership replaced the failed part. Also, front driveshaft was loose, causing the front wheel to vibrate/shake.